Display instrument and image display method

ABSTRACT

A head-mounted display device including an image display apparatus configured to display a captured image of a portion of an environment viewable through the head-mounted display device; and a dimmer configured to, while the captured image is displayed, allow a portion of ambient light from the environment to pass through the dimmer. Also, a method of displaying information on a head-mounted display device. The method may include displaying a captured image of a portion of an environment viewable through the display device; and dimming ambient light received through the head-mounted display device from the environment while displaying the captured image.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/353,110, titled “DISPLAY INSTRUMENT AND IMAGE DISPLAY METHOD,” filedon Nov. 16, 2016, which is a continuation of U.S. patent applicationSer. No. 13/875,593, titled “DISPLAY INSTRUMENT AND IMAGE DISPLAYMETHOD,” filed on May 2, 2013, which claims priority to Japanese PatentApplication Number JP 2012-107213, filed in the Japanese Patent Officeon May 9, 2012. The entire contents of each of the documents listedabove are incorporated by reference.

FIELD

The present disclosure relates to a display instrument and an imagedisplay method, and more specifically to a display instrument used as ahead mounted display (HMD) and an image display method.

BACKGROUND

In recent years, an augmented reality (AR) technique has attractedattention, in which a virtual object or a variety of information asadditional information is combined with a real environment (or a portionthereof), and the combined result is presented as electronicinformation. In order to realize this augmented reality technique, forexample, a head mounted display has been examined as an instrument forpresenting visual information. In addition, examples of applicationfields include provision of route guidance information and provision oftechnique information to an engineer who performs maintenance, which areexpected to support the work in areal environment. Particularly, thehead mounted display is very convenient since the hands are free. Inaddition, in a case where videos or images are desired to be enjoyedwhile moving outdoors as well, the videos or the images and the externalenvironment can be understood simultaneously in the range of vision, andthus smooth movement is possible.

For example, JP-A-2006-162767 discloses a virtual image displayapparatus (image display apparatus) which causes a two-dimensional imageformed by an image forming device to be observed by an observer as anenlarged virtual image using a virtual image optical system.

As shown in FIG. 29 which is a conceptual diagram, the image displayapparatus 100′ includes an image forming device 111 provided with aplurality of pixels arranged in a two-dimensional matrix state, acollimating optical system 112 which converts light emitted from thepixels of the image forming device 111 into parallel light, and anoptical device (light guide unit) 120 which guides and emits incidentlight which has been converted into the parallel light in thecollimating optical system 112. The optical device 120 includes a lightguide plate 121 which causes the incident light to propagate throughtotal reflection and to be emitted, a first deflection unit 130 (forexample, formed of a single-layer light reflection film) which reflectsthe light incident to the light guide plate 121 such that the lightincident to the light guide plate 121 is totally reflected inside thelight guide plate 121, and a second deflection unit 140 (for example,formed of multi-layer light reflection films having a multi-layerlaminate structure) which emits the light which has propagated insidethe light guide plate 121 through the total reflection, from the lightguide plate 121. In addition, if, for example, an HMD is formed usingthe image display apparatus 100′, it is possible to achieve light weightand miniaturization of the apparatus. In addition, an image displayapparatus according to Embodiment 1 described with reference to FIG. 1is referred to in relation to the reference numerals indicating otherconstituent elements in FIG. 29.

Alternatively, for example, JP-A-2007-94175 discloses a virtual imagedisplay apparatus (image display apparatus) which employs a hologramdiffraction grating in order to cause a two-dimensional image formed byan image forming device to be observed by an observer as an enlargedvirtual image using a virtual image optical system.

As shown in FIG. 30 which is a conceptual diagram, the image displayapparatus 300′ basically includes an image forming device 111 whichdisplays an image, a collimating optical system 112, and an opticaldevice (light guide unit) 320 to which light displayed in the imageforming device 111 is incident and which guides the light to the pupil21 of the observer. Here, the optical device 320 includes a light guideplate 321, and a first diffraction grating member 330 and a seconddiffraction grating member 340 formed by a reflective volume hologramdiffraction grating provided in the light guide plate 321. In addition,light emitted from each pixel of the image forming device 111 isincident to the collimating optical system 112, and thus a plurality ofparallel light beams of which angles incident to the light guide plate321 are different are generated by the collimating optical system 112and are incident to the light guide plate 321. The incident parallellight beams are emitted from a first surface 322 of the light guideplate 321. On the other hand, the first diffraction grating member 330and the second diffraction grating member 340 are installed on a secondsurface 323 of the light guide plate 321, parallel to the first surface322 of the light guide plate 321. In addition, an image displayapparatus according to Embodiment 3 described with reference to FIG. 13is referred to in relation to the reference numerals indicating otherconstituent elements in FIG. 30.

In addition, an image is displayed on the image display apparatus 100′or 300′, and thereby an observer can observe an external object and thedisplayed image in an overlapping manner. In addition, for convenience,these image display apparatuses 100′ and 300′ are referred to as“semi-transmissive image display apparatuses”.

On the other hand, for example, JP-A-2008-103916 discloses an imagedisplay apparatus of a type different from that of the above-describedimage display apparatuses. In the image display apparatus disclosedtherein, an observer can observe an image, displayed in the imagedisplay apparatus, related to the augmented reality technique but isunable to observe an external object. In addition, for convenience, thisimage display apparatus is referred to as a “non-transmissive imagedisplay apparatus”.

SUMMARY

However, in the semi-transmissive image display apparatus in the relatedart, a composite image in which an image of an external object capturedby the imaging apparatus is combined with additional information relatedthereto with high accuracy through image processing is unable to befavorably viewed via the image display apparatus without being impededby ambient light. In addition, in the non-transmissive image displayapparatus in the related art, an external object is unable to beobserved with the naked eye as described above.

Therefore, it is desirable to provide a display instrument having animage display apparatus which can be used as both of a semi-transmissiveimage display apparatus and a non-transmissive image display apparatusand enables a composite image in which an image of an external objectcaptured by an imaging apparatus is combined with additional informationrelated thereto with high accuracy through image processing to befavorably viewed via the image display apparatus without being impededby ambient light, and an image display method using the related displayinstrument.

An embodiment of the present disclosure is directed to a displayinstrument, more specifically a head mounted display (HMD), including(i) a frame that is installed on a head part of an observer; (ii) animage display apparatus that is installed in the frame; and (iii) animaging apparatus, wherein the image display apparatus includes (A) animage forming device; (B) an optical device that allows light emittedfrom the image forming device to be incident thereto, to be guided, andto be emitted therefrom; and (C) a dimming device that adjusts a lightamount of ambient light incident from the outside, and wherein, in afirst mode in which an image captured by the imaging apparatus isdisplayed on the image display apparatus, the light amount of ambientlight incident from the outside is reduced by the dimming device.

Another embodiment of the present disclosure is directed to an imagedisplay method using a display instrument including (i) a frame that isinstalled on a head part of an observer; (ii) an image display apparatusthat is installed in the frame; and (iii) an imaging apparatus, whereinthe image display apparatus includes (A) an image forming device; (B) anoptical device that allows light emitted from the image forming deviceto be incident thereto, to be guided, and to be emitted therefrom; and(C) a dimming device that adjusts a light amount of ambient lightincident from the outside, the method including causing the dimmingdevice to reduce the light amount of ambient light incident from theoutside in a first mode in which an image captured by the imagingapparatus is displayed on the image display apparatus.

In the display instrument or the image display method according to theembodiment of the present disclosure, the dimming device is providedwhich adjusts a light amount of ambient light incident from the outside,and, in the first mode in which an image captured by the imagingapparatus is displayed on the image display apparatus, the light amountof ambient light incident from the outside is reduced by the dimmingdevice. Therefore, a composite image in which an image of an externalobject captured by the imaging apparatus is combined with additionalinformation related thereto with high accuracy through an image processcan be favorably viewed via the image display apparatus without beingimpeded by ambient light.

Some embodiments are directed to a head-mounted display device. Thedevice may include an image display apparatus configured to display acaptured image of a portion of an environment viewable through thehead-mounted display device; and a dimmer configured to, while thecaptured image is displayed, allow a portion of ambient light from theenvironment to pass through the dimmer.

Some embodiments are directed to a method of displaying information on ahead-mounted display device. The method may include displaying acaptured image of a portion of an environment viewable through thedisplay device; and dimming ambient light received through thehead-mounted display device from the environment while displaying thecaptured image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a display instrument of Embodiment 1.

FIG. 2 is a schematic diagram of the display instrument of Embodiment 1and the like, viewed from the top side.

FIGS. 3A and 3B are respectively a schematic diagram of the displayinstrument of Embodiment 1 viewed from the lateral side and a schematicdiagram of optical device and dimming device parts in the displayinstrument of Embodiment 1 viewed from the front side.

FIGS. 4A and 4B are schematic cross-sectional views of the dimmingdevice schematically illustrating a behavior of the dimming device inthe display instrument of Embodiment 1.

FIG. 5 is a diagram schematically illustrating propagation of light in alight guide plate forming the image display apparatus.

FIG. 6 is a diagram illustrating the external world viewed through theoptical device (a light guide unit).

FIGS. 7A and 7B are respectively a diagram illustrating an image (animage viewed in the optical device by an observer) displayed on theimage display apparatus and a diagram illustrating a state where animage of a subject conforming to information stored in an imageinformation storage device is displayed on the image display apparatus,in a first mode.

FIG. 8 is a diagram illustrating a state where a subject viewed throughthe dimming device and the optical device or an image displayed in theoptical device and information corresponding to data regarding thesubject are displayed in an overlapping manner in a second mode.

FIG. 9 is a diagram illustrating a state where an image of the subjectis displayed so as to overlap the subject viewed through the dimmingdevice and the optical device in a third mode.

FIG. 10 is a diagram illustrating a state where an image which is aportion of an image captured by an imaging apparatus and includes aspecific subject is displayed on the image display apparatus in a thirdmode.

FIG. 11 is a diagram illustrating a state where an image of a subjectdisplayed on the image display apparatus is smaller than the subjectviewed through the dimming device and the optical device.

FIG. 12 is a conceptual diagram of an image display apparatus in adisplay instrument of Embodiment 2.

FIG. 13 is a conceptual diagram of an image display apparatus in adisplay instrument of Embodiment 3.

FIG. 14 is a schematic cross-sectional view illustrating an enlargedportion of a reflective volume hologram diffraction grating in thedisplay instrument of Embodiment 3.

FIG. 15 is a conceptual diagram of an image display apparatus in adisplay instrument of Embodiment 4.

FIG. 16 is a schematic diagram of a display instrument of Embodiment 5viewed from the front side.

FIG. 17 is a schematic diagram of the display instrument of Embodiment 5viewed from the top side.

FIGS. 18A and 18B are respectively a schematic diagram of a displayinstrument of Embodiment 6 viewed from the top side and a schematicdiagram of circuits which control an illuminance sensor.

FIGS. 19A and 19B are respectively a schematic diagram of a displayinstrument of Embodiment 7 viewed from the top side and a schematicdiagram of circuits which control an illuminance sensor.

FIG. 20 is a conceptual diagram of a display instrument of Embodiment 8.

FIG. 21 is a schematic diagram of the display instrument of Embodiment 8viewed from the top side.

FIGS. 22A and 22B are respectively a schematic diagram of the displayinstrument of Embodiment 8 viewed from the lateral side and a schematicdiagram of optical device and dimming device parts in the displayinstrument of Embodiment 8 viewed from the front side.

FIG. 23 is a conceptual diagram of a modified example of the displayinstrument of Embodiment 8.

FIG. 24 is a conceptual diagram of a display instrument of Embodiment 9.

FIG. 25 is a conceptual diagram of a display instrument of Embodiment10.

FIG. 26 is a conceptual diagram of a modified example of the displayinstrument of Embodiment 10.

FIG. 27 is a conceptual diagram of a display instrument of Embodiment11.

FIG. 28 is a conceptual diagram of a display instrument of Embodiment12.

FIG. 29 is a conceptual diagram of an image display apparatus in adisplay instrument in the related art.

FIG. 30 is a conceptual diagram of an image display apparatus in amodified example of the display instrument in the related art.

DETAILED DESCRIPTION

Hereinafter, the present disclosure will be described based onembodiments with reference to the drawings; however, the presentdisclosure is not limited to the embodiments, and various numericalvalues or materials in the embodiments are only an example. In addition,the description will be made in the following order.

1. Description of the overall display instrument and the image displaymethod according to embodiments of the present disclosure

2. Embodiment 1 (a display instrument and an image display method, andan image forming device with a first configuration)

3. Embodiment 2 (a modification of Embodiment 1)

4. Embodiment 3 (another modification of Embodiment 1, and an imageforming device with a second configuration)

5. Embodiment 4 (a modification of Embodiment 3)

6. Embodiment 5 (a modification of Embodiment 1 to Embodiment 4)

7. Embodiment 6 (a modification of Embodiment 1 to Embodiment 4)

8. Embodiment 7 (a modification of Embodiment 1 to Embodiment 4)

9. Embodiment 8 (a modification of Embodiment 1 to Embodiment 7, and adisplay instrument related to a first example of the present disclosure)

10. Embodiment 9 (a modification of Embodiment 8)

11. Embodiment 10 (another modification of Embodiment 8)

12. Embodiment 11 (a modification of Embodiment 8 to Embodiment 10)

13. Embodiment 12 (a modification of Embodiment 1 to Embodiment 7, andEmbodiment 11, and a display instrument related to a second example ofthe present disclosure), and others

[Description of Overall Display Instrument and Image Display MethodAccording to Embodiments of Present Disclosure]

In a display instrument according to an embodiment of the presentdisclosure or in a display instrument of an image display methodaccording to an embodiment of the present disclosure, the overall imageor a portion thereof captured by the imaging apparatus may be displayedin the image forming device in the first mode. In addition, in the firstmode, the image display apparatus functions as a non-transmissive type.

Alternatively, in the display instrument according to the embodiment ofthe present disclosure or in the display instrument of the image displaymethod according to the embodiment of the present disclosure, an imageinformation storage device may be further provided, and, in the firstmode, data regarding a subject imaged by the imaging apparatus may becompared with information stored in the image information storagedevice, and an image of the subject conforming to the information storedin the image information storage device may be displayed on the imagedisplay apparatus in a state where a light amount of ambient lightincident from the outside is reduced by the dimming device. In otherwords, in this case, the overall image captured by the imaging apparatusis not displayed on the image display apparatus but an image (or animage which is a portion of the image captured by the imaging apparatusand includes a specific subject) of the specific subject which is asubject conforming to the information stored in the image informationstorage device is displayed on the image display apparatus. In addition,the “data regarding a subject imaged by the imaging apparatus” mayinclude, for example, data of extracted feature points of the subjectimaged by the imaging apparatus. Further, the “information stored in theimage information storage device” may include, for example, data offeature points of various objects. Furthermore, the “comparison of thedata regarding the subject imaged by the imaging apparatus with theinformation stored in the image information storage device” may include,specifically, for example, a comparison regarding whether extractedfeature points of the subject imaged by the imaging apparatus conform tofeature points stored in the image information storage device. Inaddition, in the first mode, the data regarding the subject imaged bythe imaging apparatus may be compared with the information stored in theimage information storage device, and information corresponding to thedata regarding the subject may be displayed on the image displayapparatus. Further, the “information corresponding to the data regardingthe subject” will be described later.

In the display instrument according to the embodiment of the presentdisclosure or in the display instrument of the image display methodaccording to the embodiment of the present disclosure, including theabove-described preferable forms, in the first mode, when a light amountof ambient light incident to the dimming device is “1”, a light amountof the ambient light passing through the dimming device is 0.1 or less,and preferably 0.05 or less. Thereby, it is possible to observe an imagedisplayed on the image display apparatus without being influenced by theambient light.

Further, in the display instrument according to the embodiment of thepresent disclosure including the above-described preferable forms, animage information storage device may be further provided, and, in asecond mode different from the first mode, data regarding a subjectimaged by the imaging apparatus may be compared with information storedin the image information storage device, and information correspondingto the data regarding the subject may be displayed on the image displayapparatus in a state where a light amount of ambient light incident fromthe outside is not reduced by the dimming device. In addition, in thesecond mode, the image display apparatus functions as asemi-transmissive type. The “information corresponding to the dataregarding the subject” may include, for example, a character, asentence, a figure, an illustration, a still image, a picture, a movingimage, and the like. This is also the same for the following.

Alternatively, in the image display method according to the embodimentof the present disclosure including the above-described preferableforms, an image information storage device may be further provided, and,in a second mode after an operation in the first mode, data regarding asubject imaged by the imaging apparatus may be compared with informationstored in the image information storage device, and informationcorresponding to the data regarding the subject may be displayed on theimage display apparatus in a state where a light amount of ambient lightincident from the outside is not reduced by the dimming device.

In addition, in this configuration in the display instrument or theimage display method according to the embodiment of the presentdisclosure, in the second mode, information corresponding to the dataregarding the subject may be displayed on the image display apparatus soas to overlap the subject viewed through the dimming device and theoptical device or around the subject. Further, in this configuration inthe display instrument or the image display method according to theembodiment of the present disclosure, a microphone may be furtherprovided, and, switching between the first mode and the second mode maybe controlled by inputting sound using the microphone. Specifically,switching between the first mode and the second mode may be controlledin response to an instruction based on an observer's voice.Alternatively, an infrared-ray emitting and receiving device may befurther provided, and switching between the first mode and the secondmode may be controlled using the infrared-ray emitting and receivingdevice. Specifically, the switching between the first mode and thesecond mode may be controlled by detecting blinking of an observer usingthe infrared-ray emitting and receiving device.

In addition, in this configuration of the display instrument or thedisplay instrument in the image display method according to theembodiment of the present disclosure, in the second mode, when a lightamount of ambient light incident to the dimming device is “1”, a lightamount of the ambient light passing through the dimming device is 0.3 to0.8, and preferably 0.5 to 0.8. Thereby, it is possible to clearlyobserve an external object and an image displayed on the image displayapparatus.

In addition, in the display instrument according to the embodiment ofthe present disclosure including the above-described preferable formsand configurations, an image information storage device may be furtherprovided, and, in a third mode different from the first mode (and thesecond mode), data regarding a subject imaged by the imaging apparatusmay be compared with information stored in the image information storagedevice, and an image (this image is stored in the image informationstorage device) of the subject having data corresponding to informationstored in the image information storage device may be displayed on theimage display apparatus in a state where a light amount of ambient lightincident from the outside is not reduced by the dimming device. Inaddition, in the third mode, the image display apparatus functions as asemi-transmissive type.

In addition, in the image display method according to the embodiment ofthe present disclosure including the above-described preferable formsand configurations, the image display apparatus may further include animage information storage device, and, in the third mode after anoperation in the first mode (and/or the second mode), data regarding asubject imaged by the imaging apparatus may be compared with informationstored in the image information storage device, and an image (this imageis stored in the image information storage device) of the subject havingdata corresponding to information stored in the image informationstorage device may be displayed on the image display apparatus in astate where a light amount of ambient light incident from the outside isnot reduced by the dimming device.

In addition, in this configuration of the display instrument or thedisplay instrument in the image display method according to theembodiment of the present disclosure, in the third mode, when a lightamount of ambient light incident to the dimming device is “1”, a lightamount of the ambient light passing through the dimming device is 0.1 to0.6, and preferably 0.3 to 0.4. Thereby, it is possible to clearlyobserve an external object and an image displayed on the image displayapparatus.

In the third mode including the above-described preferableconfigurations, an image of the subject displayed on the image displayapparatus may be adjusted so as to overlap the subject viewed throughthe dimming device and the optical device with the image of the subjectdisplayed on the image display apparatus. The adjustment of the image ofthe subject displayed on the image display apparatus may includeenlargement and reduction processes, a rotation process and a movementprocess of the image, and, specifically, an image data process may beperformed based on an affine transform matrix. This is also the same forthe following. Alternatively, in the third mode including theabove-described preferable configurations, an image of the subjectdisplayed on the image display apparatus may be adjusted such that theimage of the subject displayed on the image display apparatus is smallerthan the subject viewed through the dimming device and the opticaldevice.

In the display instrument or in the display instrument in the imagedisplay method according to the embodiment of the present disclosureincluding the above-described preferable forms and configurations, apair of image display apparatuses installed in a frame may be provided,and one of the image display apparatuses may be in a state where a lightamount of ambient light incident from the outside is not reduced by thedimming device at all times.

In the display instrument or in the display instrument in the imagedisplay method according to the embodiment of the present disclosure(hereinafter, they are collectively simply referred to as a “displayinstrument or the like” according to the embodiment of the presentdisclosure) including the above-described preferable forms andconfigurations, the dimming device may be disposed in the opticaldevice, and, specifically, the dimming device may be disposed on anopposite side (opposite surface) to a side where the image formingdevice is disposed in the optical device. In addition, the dimmingdevice may include a light shutter in which a light transmission controlmaterial layer is formed of a liquid crystal material layer, or thedimming device may include a light shutter in which the lighttransmission control material layer is formed of an inorganicelectroluminescence material layer. However, the dimming device is notlimited thereto, and the dimming device may use a light shutter whichincludes a plurality of charged electrophoretic particles and anelectrophoretic dispersion liquid formed by electrophoretic dispersionmedia having colors different from those of the electrophoreticparticles; a light shutter according to an electrodeposition methodemploying electrodeposition and dissociation phenomena caused by areversible oxidation-reduction reaction of a metal (for example, silverparticles); a light shutter employing a color variation of a materialcaused by the oxidation-reduction reaction of an electrochromicmaterial; and a light shutter which controls light transmittance usingan electrowetting phenomenon. Here, in a case where the dimming deviceincludes the light shutter in which a light transmission controlmaterial layer is formed of a liquid crystal material layer, a materialconstituting the light transmission control material layer may include,for example, a TN (Twisted Nematic) type liquid crystal material, an STN(Super Twisted Nematic) type liquid crystal material, or the like,although not being limited thereto. In addition, in a case where thedimming device includes the light shutter in which the lighttransmission control material layer is formed of an inorganicelectroluminescence material layer, a material constituting the lighttransmission control material layer may include, for example, tungstenoxide (WO₃) although not being limited thereto. Further, the opticaldevice and the dimming device are preferably disposed in this order froman observer side; however, the dimming device and the optical device maybe disposed in this order.

A light blocking member which blocks ambient light from being incidentto the optical device may be disposed in a region of the optical deviceto which light emitted from the image forming device is incident. Forconvenience, this configuration is referred to as a “display instrumentrelated to a first example of the present disclosure”. In the displayinstrument related to the first example of the present disclosure, thelight blocking member which blocks ambient light from being incident tothe optical device may be disposed in a region of the optical device towhich light emitted from the image forming device is incident. Thereby,since the ambient light is not originally incident to the region of theoptical device to which light emitted from the image forming device isincident even if an incident light amount of the ambient light variesdue to an operation of the dimming device, there is no deterioration inimage display quality due to occurrence of undesired stray light or thelike in the display instrument. In addition, the region of the opticaldevice to which light emitted from the image forming device is incidentis preferably included in an image in which the light blocking member isprojected onto the optical device.

The light blocking member may be disposed apart from the optical deviceon an opposite side to the side where the image forming device isdisposed in the optical device. In the display instrument with thisconfiguration, the light blocking member may be manufactured using, forexample, an opaque plastic material. This light blocking member mayintegrally extend from a casing of the image display apparatus or beinstalled in the casing of the image display apparatus, or mayintegrally extend from the frame or be installed in the frame.Alternatively, the light blocking member may be disposed in the opticaldevice part on an opposite side to the side where the image formingdevice is disposed, or the light blocking member may be disposed in thedimming device. In addition, the light blocking member made of an opaquematerial may be formed on the surface of the optical device using aphysical vapor deposition method (a PVD method), a chemical vapordeposition method (a CVD method), or using a printing method, or may beformed by bonding a film, a sheet or a foil made of an opaque material(a plastic material, a metal material, an alloy material, or the like)thereon. A projection image of an end portion of the dimming device ontothe optical device is preferably included in a projection image of thelight blocking member onto the optical device.

Alternatively, the dimming device may include a first substrate oppositeto an optical device; a second substrate opposite to the firstsubstrate; a first electrode and a second electrode respectivelyprovided on the first substrate and the second substrate; and a lighttransmission control material layer sealed between the first substrateand the second substrate, and the first substrate may also be used as aconstituent member of the optical device. For convenience, thisconfiguration is referred to as a “display instrument related to asecond example of the present disclosure”. In the display instrumentrelated to the second example of the present disclosure, the firstsubstrate forming the dimming device is also used as a constituentmember of the optical device. Thereby, the weight of the entire displayinstrument can be reduced, and thus there is no concern that a user ofthe display instrument may feel discomfort. In addition, the secondsubstrate may be thinner than the first substrate.

Materials of the first substrate and the second substrate may include,specifically, a transparent glass substrate such as soda-lime glass orsuper white glass, a plastic substrate, and a plastic sheet, a plasticfilm. Here, the plastic may include polyethylene terephthalate,polyethylene naphtalate, polycarbonate, cellulose esters such ascellulose acetate, fluoropolymers such as a copolymer of polyvinylidenefluoride or polytetrafluoroethylene and hexafluoropropylene, polyetherssuch as polyoxymethylene, polyolefins such as polyacetal, polystyrene,polyethylene, polypropylene or methylpentene polymer, polyimides such aspolyamidoimide or polyetherimide, polyamide, polyethersulfone,polyphenylene sulfide, polyvinylidene fluoride, tetra-acetylcelluose,phenoxy bromide, polyarylate, polysulfone, and the like. The plasticsheet and the plastic film may be rigid so as not to be easily bent, ormay be flexible. In a case where the first substrate and the secondsubstrate are formed of a transparent plastic substrate, a barrier layermade of an inorganic material or an organic material may be formed on aninner surface of the substrate.

The first electrode and the second electrode formed on the firstsubstrate and the second substrate may be a so-called transparentelectrode, and, specifically, may use indium tin oxide (ITO, includingSn-doped In₂O₃, crystalline ITO, and amorphous ITO), fluorine-doped SnO₂(FTO)), IFO (F-doped In₂O₃), antimony-doped SnO₂ (ATO), SnO₂, ZnO(including Al-doped ZnO or B-doped ZnO), indium zinc oxide (IZO), spineloxide, oxide with a YbFe₂O₄ structure, conductive polymers such aspolyaniline, polypyrrole or polythiophene, and the like, but are notlimited thereto, and may use combinations of two kinds or more thereof.The first electrode and the second electrode may be formed using aphysical vapor deposition method (PVD method) such as a vacuumdeposition method or a sputtering method, various chemical vapordeposition methods (CVD methods), and various coatings. Patterning ofthe electrode is not basically necessary; however, in a case wherepatterning is performed as necessary, the patterning may be performedusing any method such as an etching method, a lift-off method, or amethod using various masks.

The first substrate and the second substrate are sealed and adhered toeach other in the outer edge part by a sealing agent. The sealing agentmay use a variety of resins, for example, heat-cured type, light-curedtype, moisture-cured type, and anaerobic-cured type resins, such as anepoxy resin, a urethane resin, an acryl resin, a vinyl acetate resin, anenethiol resin, a silicone resin, and a degeneration polymer resin.

A first illuminance sensor (for convenience, referred to as an“environmental illuminance measuring sensor” in some cases) whichmeasures illuminance of the environment in which the display instrumentis placed may be further provided, and, based on a measurement result ofthe first illuminance sensor, light transmittance of the dimming devicemay be controlled, or luminance of an image formed by the image formingdevice may be controlled. Alternatively, a second illuminance sensor(for convenience, referred to as a “transmission light illuminancemeasuring sensor” in some cases) which measures illuminance based onlight transmitted through the dimming device from the externalenvironment may be further provided, and, based on a measurement resultof the second illuminance sensor, light transmittance of the dimmingdevice may be controlled, or luminance of an image formed by the imageforming device may be controlled. Here, the second illuminance sensor ispreferably disposed further toward an observer side than the opticaldevice.

As described above, since the transmittance of the dimming device iscontrolled and the luminance of an image formed by the image formingdevice is controlled based on a measurement result of the firstilluminance sensor, and the transmittance of the dimming device iscontrolled and the luminance of an image formed by the image formingdevice is controlled based on a measurement result of the secondilluminance sensor, it is possible to not only give high contrast to animage observed by an observer but also to optimize an observation stateof the image depending on the illuminance of the peripheral environmentin which the display instrument is placed. The illuminance sensors (theenvironmental illuminance measuring sensor and the transmitted lightilluminance measuring sensor) may be formed using existing illuminancesensors, and the illuminance sensors may be controlled using existingcontrol circuits.

In addition, when a measurement result of the first illuminance sensoris equal to or more than a predetermined value (for convenience,referred to as a “first illuminance measurement value” in some cases),the light transmittance of the dimming device may be made to be equal toor less than a predetermined value (for convenience, referred to as a“first light transmittance” in some cases). Alternatively, when ameasurement result of the first illuminance sensor is equal to or lessthan a predetermined value (for convenience, referred to as a “secondilluminance measurement value” in some cases), the light transmittanceof the dimming device may be made to be equal to or more than apredetermined value (for convenience, referred to as a “second lighttransmittance” in some cases). Further, in a case where the measurementresult of the second illuminance sensor is not a desired illuminance inview of the illuminance of the first illuminance sensor, or subtlerilluminance adjustment is desired, the light transmittance of thedimming device may be adjusted while monitoring a value of the secondilluminance sensor. Here, the first illuminance measurement value may be10 lux, the first light transmittance may be any one of 1% to 30%, thesecond illuminance measurement value may be 0.01 lux, and the secondlight transmittance may be any one of 51% to 99%. In addition, in a casewhere an illuminance measurement value of the first illuminance sensoris 1×10⁻³ lux or less, for example, a driving voltage of the dimmingdevice is preferably controlled so as to reduce a driving time, therebyincreasing the light transmittance of the dimming device as rapidly aspossible.

Further, light transmitted through the dimming device may be colored ina desired color by the dimming device depending on cases. In addition,in these cases, a color of light colored by the dimming device may bevariable, or a color of light colored by the dimming device may befixed. In addition, in a case of the former, for example, a dimmingdevice which colors light red, a dimming device which colors lightgreen, and a dimming device which colors light blue may be laminated.Further, in a case of the latter, a color of light colored by thedimming device may be brown although is not limited thereto.

In addition, the dimming device may be disposed so as to be freelyattachable and detachable depending on cases. In order to dispose thedimming device so as to be attachable and detachable, for example, thedimming device may be installed in, for example, the frame using screwsmade of transparent plastic, the frame may be cut so as to form groovesand the dimming device may be engaged with the grooves, magnets may beinstalled in the frame and the dimming device may be installed in theframe, or slide portions may be provided in the frame and the dimmingdevice may be fitted and inserted into the slide portions. In addition,a connector may be installed in the dimming device, and the dimmingdevice may be electrically connected to the control circuit (forexample, included in a control device for controlling the image formingdevice) for controlling the light transmittance of the dimming devicevia the connector and wires. The dimming device may be curved.

Further, in the display instrument or the like according to theembodiment of the present disclosure including the above-describedvarious preferable forms and configurations, the optical device mayinclude (a) a light guide plate which allows incident light to propagatethe inside thereof through total reflection, to be guided, and to beemitted therefrom, (b) a first deflection unit which deflects lightincident to the light guide plate such that the light incident to thelight guide plate is totally reflected inside the light guide plate, and(c) a second deflection unit which causes the light which has propagatedinside the light guide plate through the total reflection to undergo aplurality of deflections in order to emit the light which has propagatedinside the light guide plate through the total reflection from the lightguide plate. The term “total reflection” indicates total internalreflection or total reflection inside the light guide plate. This isalso the same for the following. In addition, in this case, the seconddeflection unit may be located in a projection image of the dimmingdevice, or the dimming device may be located in a projection image ofthe second deflection unit. Further, as described above, the firstdeflection unit and the second deflection unit may be covered by one(the first substrate) of the substrates forming the dimming device.

In the display instrument or the like according to the embodiment of thepresent disclosure including the above-described various preferableforms and configurations, the optical device is of a semi-transmissivetype (see-through type). Specifically, at least the optical device partfacing the pupil of an observer is semi-transmissive (see-through),thereby allowing viewing of the outside via the optical device part. Thedisplay instrument may include a single image display apparatus or twoimage display apparatuses.

Here, the first deflection unit may reflect light incident to the lightguide plate, and the second deflection unit may cause the light whichhas propagated inside the light guide plate through total reflection toundergo a plurality of transmissions and reflections. In addition, inthis case, the first deflection unit may function as a reflectivemirror, and the second deflection unit may function as asemi-transmissive mirror.

In this configuration, the first deflection unit may include, forexample, a light reflection film (a kind of mirror) which is made ofmetal including an alloy and reflects light incident to the light guideplate, or a diffraction grating (for example, a hologram diffractiongrating film) which diffracts light incident to the light guide plate.In addition, the second deflection unit may include a multi-layerlaminate structure in which a plurality of dielectric laminate films arelaminated, a half mirror, a polarization beam splitter, or a hologramdiffraction grating film. Further, the first deflection unit and thesecond deflection unit are disposed inside the light guide plate (builtin the light guide plate), and, in the first deflection unit, parallellight incident to the light guide plate is reflected or diffracted suchthat the parallel light incident to the light guide plate is totallyreflected inside the light guide plate. On the other hand, in the seconddeflection unit, the parallel light which propagates inside the lightguide plate through the total reflection undergoes a plurality of linearreflections or diffractions, and is then emitted from the light guideplate in a parallel light state.

Alternatively, the first deflection unit may diffract light incident tothe light guide plate, and the second deflection unit may cause thelight which has propagated inside the light guide plate through thetotal reflection to undergo a plurality of diffractions. In addition, inthis case, the first deflection unit and the second deflection unit mayinclude diffraction grating elements. Further, the diffraction gratingelements may be formed by a reflective diffraction grating element or atransmissive diffraction grating element, or one of the diffractiongrating elements may be formed by a reflective diffraction gratingelement, and the other thereof may be formed by a transmissivediffraction grating element. In addition, the reflective diffractiongrating element may include a reflective volume hologram diffractiongrating. For convenience, the first deflection unit formed by thereflective volume hologram diffraction grating is referred to as a“first diffraction grating member”, and, for convenience, the seconddeflection unit formed by the reflective volume hologram diffractiongrating is referred to as a “second diffraction grating member”.

An image may be displayed in a single color (for example, green) by theimage display apparatus according to the embodiment of the presentdisclosure; however, in a case of displaying an image in color, thefirst diffraction grating member or the second diffraction gratingmember may be formed by laminating P diffraction grating layersincluding the reflective volume hologram diffraction grating so as tocorrespond to diffractive reflection of the P kinds of light beamshaving the P kinds (for example, P is 3 and the three kinds of red,green and blue) of different wavelength bands (or wavelengths). Aninterference pattern corresponding to one kind of wavelength band (orwavelength) is formed on each diffraction grating layer. Alternatively,the P kinds of interference patterns may be formed in the firstdiffraction grating member or the second diffraction grating memberwhich includes a single diffraction grating layer in order to correspondto diffractive reflection of the P kinds of light beams having the Pkinds of different wavelength bands (or wavelengths). Alternatively, anangle of view may be equally divided into, for example, three, and thefirst diffraction grating member or the second diffraction gratingmember may be formed by laminating diffraction grating layerscorresponding to the respective angles of view. Alternatively, forexample, a structure may be employed in which the first diffractiongrating member and the second diffraction grating member including adiffraction grating layer formed by a reflective volume hologramdiffraction grating which diffracts and reflects light with a redwavelength band (or wavelength) are disposed in a first light guideplate, the first diffraction grating member and the second diffractiongrating member including a diffraction grating layer formed by areflective volume hologram diffraction grating which diffracts andreflects light with a green wavelength band (or wavelength) are disposedin a second light guide plate, the first diffraction grating member andthe second diffraction grating member including a diffraction gratinglayer formed by a reflective volume hologram diffraction grating whichdiffracts and reflects light with a blue wavelength band (or wavelength)are disposed in a third light guide plate, and the first light guideplate, the second light guide plate, and the third light guide plate maybe laminated with a gap therebetween. In addition, by employing thisconfiguration, it is possible to increase diffraction efficiency,increase a diffraction acceptance angle and optimize a diffraction anglewhen the light with each wavelength band (or a wavelength) is diffractedand reflected in the first diffraction grating member or the seconddiffraction grating member. A protection member is preferably disposedsuch that the reflective volume hologram diffraction grating does notdirectly contact the air.

A material of the first diffraction grating member and the seconddiffraction grating member may be a photopolymer material. A constituentmaterial or a basic structure of the first diffraction grating memberand the second diffraction grating member including the reflectivevolume hologram diffraction grating may be the same as a constituentmaterial or a structure of a reflective volume hologram diffractiongrating in the related art. The reflective volume hologram diffractiongrating indicates a hologram diffraction grating which diffracts andreflects only diffraction light of +1 order. In the diffraction gratingmember, an interference pattern is formed from the surface to theinside, and a forming method of the related interference pattern itselfmay be the same as a forming method in the related art. Specifically,for example, a member (for example, a photopolymer material) forming thediffraction grating member may be irradiated with object light from afirst predetermined direction on one side, and, simultaneously, themember forming the diffraction grating member may be irradiated withreference light from a second predetermined direction on the other side,such that an interference pattern formed by the object light and thereference light is recorded inside the member forming the diffractiongrating member. The first predetermined direction, the secondpredetermined direction, and wavelengths of the object light and thereference light may be appropriately selected, thereby obtaining adesired pitch of the interference pattern and a desired slant angle onthe surface of the diffraction grating member. The slant angle of theinterference pattern indicates an angle formed between a surface of thediffraction grating member (or the diffraction grating layer) and theinterference pattern. In a case where the first diffraction gratingmember and the second diffraction grating member include a laminatestructure of P diffraction grating layers formed by the reflectivevolume hologram diffraction grating, in relation to the lamination ofthe diffraction grating layers, P diffraction grating layers may bemanufactured separately, and the P diffraction grating layers may belaminated (adhered) using, for example, an ultraviolet-cured adhesive.In addition, after a single diffraction grating layer is manufacturedusing a photopolymer material having the adhesiveness, diffractiongrating layers may be manufactured by sequentially adhering photopolymermaterials having the adhesiveness thereon, thereby manufacturing the Pdiffraction grating layers.

Alternatively, in the image display apparatus according to theembodiment of the present disclosure, the optical device may include asemi-transmissive mirror which allows light emitted from the imageforming device to be incident thereto and to be emitted therefrom towardthe pupil of an observer. In addition, the light emitted from the imageforming device may propagate through the air and be incident to thesemi-transmissive mirror, or may propagate inside a transparent membersuch as, for example, a glass plate or a plastic plate (specifically, amember made of the same material as a material of a light guide platedescribed later) and be incident to the semi-transmissive mirror.Further, the semi-transmissive mirror may be installed in the imageforming device via the transparent member, or the semi-transmissivemirror may be installed in the image forming device via a member otherthan the transparent member.

In the image display apparatus according to the embodiment of thepresent disclosure including the above-described various preferableforms and configurations, the image forming device may include aplurality of pixels arranged in a two-dimensional matrix state. Inaddition, this configuration of the image forming device is referred toas an “image forming device with a first configuration”.

The image forming device with the first configuration may include, forexample, an image forming device constituted by a reflective spatiallight modulation device and a light source; an image forming deviceconstituted by a transmissive spatial light modulation device and alight source; and an image forming device constituted by a lightemitting element such as an organic EL (ElectroLuminescence), aninorganic EL, or a light emitting diode (LED), and, among them, theimage forming device constituted by a reflective spatial lightmodulation device and a light source is preferable. The spatial lightmodulation device may include a light valve, for example, a transmissiveor reflective liquid crystal display such as an LCOS (Liquid Crystal OnSilicon) and a digital micromirror device (DMD), and the light sourcemay include a light emitting element. Further, the reflective spatiallight modulation device may include a liquid crystal display, and apolarization beam splitter which reflects some of light beams from alight source so as to be guided to the liquid crystal display andtransmits some of light beams reflected by the liquid crystal display soas to be guided to an optical system. The light emitting element formingthe light source may include a red light emitting element, a green lightemitting element, a blue light emitting element, and a white lightemitting element. Alternatively, red light, green light, and blue lightwhich are respectively emitted from a red light emitting element, agreen light emitting element, and a blue light emitting element may bemixed and undergo luminance uniformity by a light pipe, therebyobtaining white light. As the light emitting element, for example, asemiconductor laser element or a solid-state laser, and an LED may beexemplified. The number of pixels may be determined based onspecifications required by the image display apparatus, the detailedvalues of the number of pixels may exemplify 320×240, 432×240, 640×480,1024×768, 1920×1080, and the like.

Alternatively, in the image display apparatus according to theembodiment of the present disclosure including the above-describedpreferable forms and configurations, the image forming device mayinclude a light source, and a scanning unit which scans parallel lightemitted from the light source. In addition, for convenience, theconfiguration of the image forming device is referred to as an “imageforming device with a second configuration”.

In the image forming device with the second configuration, a lightemitting element is used as the light source, and, specifically, a redlight emitting element, a green light emitting element, a blue lightemitting element, and a white light emitting element may be used.Alternatively, red light, green light, and blue light which arerespectively emitted from a red light emitting element, a green lightemitting element, and a blue light emitting element may be mixed andundergo luminance uniformity by a light pipe, thereby obtaining whitelight. As the light emitting element, for example, a semiconductor laserelement or a solid-state laser, and an LED may be exemplified. Thenumber of pixels (virtual pixels) of the image forming device with thesecond configuration may also be determined based on specificationsrequired by the image display apparatus, and the detailed values of thenumber of pixels (virtual pixels) may be exemplified by 320×240,432×240, 640×480, 1024×768, 1920×1080, and the like. In a case where animage is displayed in color, and the light source is constituted by ared light emitting element, a green light emitting element, and a bluelight emitting element, colors are preferably combined using, forexample, a cross prism. The scanning unit may use MEMS (Micro ElectroMechanical Systems) or a galvanic mirror which scans light emitted froma light source horizontally and vertically and has, for example, amicromirror capable of rotating in a two-dimensional direction.

In the image forming device with the first configuration or the imageforming device with the second configuration, light which is convertedinto a plurality of parallel light beams in the optical system (theoptical system converts emitted light into parallel light and isreferred to as a “parallel light emitting optical system” in some cases,and may be specifically, for example, a collimating optical system or arelay optical system) is incident to the light guide plate, and, thisdemand for the parallel light is based on it being necessary for lightwave surface information when the light is incident to the light guideplate to be preserved even after the light is emitted from the lightguide plate via the first deflection unit and the second deflectionunit. In addition, in order to generate a plurality of parallel lightbeams, specifically, for example, a light emitting portion of the imageforming device may be disposed, for example, at a location (position)corresponding to a focal length of the parallel light emitting opticalsystem. The parallel light emitting optical system has a function ofconverting position information of a pixel into angle information in theoptical system of the optical device. The parallel light emittingoptical system may exemplify an optical system which has positiveoptical power as a whole by using a convex lens, a concave lens, afree-form-surface prism, and a holographic lens, singly or together. Alight blocking portion having an opening may be disposed between theparallel light emitting optical system and the light guide plate inorder to prevent a case where undesired light is emitted from theparallel light emitting optical system and is incident to the lightguide plate.

The light guide plate has two parallel surfaces (a first surface and asecond surface) extending in parallel to the axial line (X axis) of thelight guide plate. When the surface of the light guide plate to whichlight is incident is a light guide plate incidence surface, and thesurface of the light guide plate from which light is emitted is a lightguide plate emission surface, the first surface may form the light guideplate incidence surface and the light guide plate emission surface, orthe first surface may form the light guide plate incidence surface, andthe second surface may form the light guide plate emission surface. Amaterial of the light guide plate may use glass including optical glasssuch as quartz glass or BK7, or a plastic material (for example, PMMA, apolycarbonate resin, an acryl resin, an amorphous polypropylene resin, astyrene resin including an AS resin). A shape of the light guide plateis not limited to a plate shape and may be a curved shape.

In the display instrument or the like according to the embodiment of thepresent disclosure, the frame may include a front portion which isdisposed on the front side of an observer, and two temple portions whichare installed in both ends of the front portion via hinges so as to berotatable. In addition, a modern portion is installed in a front endpart of each temple portion. Although the image display apparatus isinstalled in the frame, specifically, for example, the image formingdevice may be installed in the temple portions. Further, the frontportion and the two temple portions may be integrally formed. In otherwords, when the overall display instrument according to the embodimentof the present disclosure is viewed, the frame generally hassubstantially the same structure as glasses. A material of the frameincluding a pad portion may use the same material as a material oftypical glasses, such as a metal, an alloy, plastic, and a combinationthereof. Further, a nose pad may be installed in the front portion. Inother words, when the overall display instrument or the like accordingto the embodiment of the present disclosure is viewed, an assembly ofthe frame and the nose pad has substantially the same structure astypical glasses except that there is no rim. The nose pad may also haveexisting configurations and structures.

In addition, in the display instrument or the like according to theembodiment of the present disclosure, from the viewpoint of design oreasiness of installation, wires (a signal line, a power supply line, andthe like) of one or two image forming devices preferably extend outwardfrom the front end part of the modern portion via the insides of thetemple portion and the modern portion and are connected to the controldevice (a control circuit or a control unit). Further, each imageforming device includes a headphone portion, and wires for the headphoneportion from each image forming device may extend from the front endpart of the modern portion to the headphone portion via the templeportion and the inside of the modern portion. The headphone portion mayuse, for example, an inner ear type headphone portion, or a canal typeheadphone portion. Preferably, more specifically, the wire for theheadphone portion extends from the front end part of the modern portionto the headphone portion so as to go around the back side of theauricle.

The imaging apparatus may be installed at the central part of the frontportion. The imaging apparatus includes, specifically, a solid-stateimaging element formed by, for example, a CCD or a CMOS sensor, and alens. Wires from the imaging apparatus may be connected to one of theimage display apparatuses (or the image forming devices) via, forexample, the front portion, and, further, may be included in wiresextending from the image display apparatus (or the image formingdevice).

Light beams which are emitted from the center of the image formingdevice and pass through a node on the image forming device side of theoptical system are referred to as “central light beams”, and, among thecentral light beams, a central light beam which is perpendicularlyincident to the optical device is referred to as a “central incidentlight beam”. In addition, a point where the central incident light beamis incident to the optical device is set as a central point of theoptical device, an axial line which passes through the central point ofthe optical device and is parallel to the axial line direction of theoptical device is set as an X axis, and an axial line which passesthrough the central point of the optical device and conforms to thenormal line of the optical device is set as a Y axis. A horizontaldirection in the display instrument or the like according to theembodiment of the present disclosure is a direction parallel to the Xaxis, and is hereinafter referred to as an “X axis direction” in somecases. Here, the optical system is disposed between the image formingdevice and the optical device and converts light emitted from the imageforming device into parallel light. In addition, a light flux convertedinto the parallel light in the optical system is incident to the opticaldevice, is guided and is emitted therefrom. Further, a central point ofthe first deflection unit is set as an “optical device central point”.

The display instrument or the like according to the embodiment of thepresent disclosure including the above-described various modifiedexamples may be used for display of, for example, various descriptions,or symbols, signs, marks, labels, designs, and the like when observationtargets (subjects) such as various devices are worked, operated,maintained, and dismantled; display of various descriptions, or symbols,signs, marks, labels, designs, and the like regarding observationtargets (subjects) such as persons or products; display of moving imagesor still images; display of subtitles of a movie or the like; display ofan explanation or a closed caption regarding a picture synchronized withthe picture; display of various descriptions regarding observationtargets (subjects) in a play or a kabuki play, a noh play, a comedicdrama, an opera, a concert, a ballet, various theaters, an amusementpark, an art gallery, a tourist spot, a resort area, travel guidance,and the like, and an explanation for explaining content, progress,background thereof, or the like, or display of closed captions. Inaddition, the above-described variety of content represents informationcorresponding to data regarding a subject. In a play or a kabuki play, anoh play, a comedic drama, an opera, a concert, a ballet, varioustheaters, an amusement park, an art gallery, a tourist spot, a resortarea, travel guidance, and the like, characters related to anobservation target may be displayed as an image on the displayinstrument at an appropriate timing. Specifically, according to aprogress of a movie or the like, or according to a progress of a theaterproduction or the like, an image control signal is sent to the displayinstrument, and an image is displayed on the display instrument, by anoperator's operation or under the control of a computer or the like,based on a predetermined schedule and allocation of time. In addition,although display of various descriptions regarding observation targets(subjects) such as various devices, persons or products is performed,observation targets (subjects) such as various devices, persons orproducts may be imaged by the imaging apparatus, and the imaged contentis analyzed in the display instrument, thereby various descriptions,created in advance, regarding the observation targets (subjects) such asvarious devices, persons or products may be displayed on the displayinstrument. Alternatively, the display instrument or the like accordingto the embodiment of the present disclosure may be used as astereoscopic display instrument. In this case, a polarization plate or apolarization film may be installed in the optical device so as to beattachable and detachable, or a polarization plate or a polarizationfilm may be bonded to the optical device, depending on cases.

Image signals applied to the image forming device may include not onlyan image signal (for example, character data) but also, for example,luminance data (luminance information) regarding an image to bedisplayed, or chromaticity data (chromaticity information), or luminancedata and chromaticity data. The luminance data may be luminance datacorresponding to the luminance of a predetermined region including anobservation target viewed through the optical device, and thechromaticity data may be chromaticity data corresponding to thechromaticity of a predetermined region including an observation targetviewed through the optical device. As above, the luminance dataregarding an image is included, thereby controlling the luminance(brightness) of the displayed image, the chromaticity data regarding animage is included, thereby controlling the chromaticity (color) of thedisplayed image, and the luminance data and the chromaticity dataregarding an image are included, thereby controlling the luminance(brightness) and the chromaticity (color) of the displayed image. In acase of using luminance data corresponding to the luminance of apredetermined region including an observation target viewed through theimage display apparatus, a value of the luminance data may be set suchthat the higher the value of the luminance of the predetermined regionincluding the observation target viewed through the image displayapparatus, the higher the value of the luminance of the image (that is,the more brightly the image is displayed). In a case of usingchromaticity data corresponding to the chromaticity of a predeterminedregion including an observation target viewed through the image displayapparatus, a value of the chromaticity data may be set such that thechromaticity of the predetermined region including the observationtarget viewed through the image display apparatus and the chromaticityof an image to be displayed have a substantially complementary colorrelationship. The complementary color indicates a combination of colorslocated directly opposite to each other in the color circle. Examples ofthe complementary colors include red and green, yellow and violet, blueand orange, and the like. Although a color causing chroma reduction isalso specified like white in a case of light and black in a case of anobject when a certain color is mixed with other colors at an appropriateratio, the visual effect complementation when colors are arranged inparallel is different from the visual effect complementation when thecolors are mixed. The colors are also called complemental colors,contrasting colors, or opposite colors. However, the opposite colorsdirectly indicate opposite colors, whereas a range indicated by thecomplementary colors is a slightly wider. A combination of complementarycolors causes the synergistic effect of uniting the colors so as tosupport each other, which is called complementary color harmony.

Embodiment 1

Embodiment 1 relates to a display instrument and an image display methodaccording to embodiment of the present disclosure. FIG. 1 is aconceptual diagram illustrating an image display apparatus according toEmbodiment 1; FIG. 2 is a schematic diagram of the display instrument(specifically, a head mounted display (HMD)) of Embodiment 1 and thelike, viewed from the top side; FIG. 3A is a schematic diagram of thedisplay instrument viewed from the lateral side; FIG. 3B is a schematicdiagram of optical device and dimming device parts viewed from the frontside; and FIGS. 4A and 4B are schematic cross-sectional views of thedimming device schematically illustrating a behavior of the dimmingdevice in the display instrument of Embodiment 1. In addition, FIG. 5 isa diagram schematically illustrating propagation of light in a lightguide plate forming the image display apparatus.

The display instrument of Embodiment 1 or Embodiments 2 to 12 describedlater is more specifically a head mounted display (HMD), and includes(i) a frame (for example, a glasses-type frame 10) worn on the head partof an observer, (ii) an image display apparatus 100, 200, 300, 400 or500 installed in the frame 10, and (iii) an imaging apparatus 17. Inaddition, although the display instrument of Embodiment 1 or Embodiments2 to 12 described later is, specifically, of a binocular type in whichtwo image display apparatuses are provided, the display instrument maybe of a monocular type in which a single image display apparatus isprovided. In addition, the image forming device 111 or 211 displays, forexample, a monochrome (for example, green) image.

In addition, the image display apparatus 100, 200, 300, 400 or 500 inEmbodiment 1 or Embodiments 2 to 12 described later includes (A) theimage forming device 111 or 211, (B) an optical device (a light guideunit) 120, 320 or 520 which allows light emitted from the image formingdevice 111 or 211 to be incident thereto, to be guided, and to beemitted therefrom, (C) a dimming device 700 which adjusts a light amountof ambient light incident from the outside, and (D) an optical system(parallel light emitting optical system) 112 or 254 which converts lightemitted from the image forming device 111 or 211 into parallel light.Here, a light flux which has been converted into parallel light in theoptical system 112 or 254 is incident to, is guided, and is emitted fromthe optical device 120, 320 or 520.

In addition, the image display apparatus 100, 200, 300, 400 or 500 maybe installed in the frame so as to be fixed, or may be installed so asto be attachable and detachable. Here, the optical system 112 or 254 isdisposed between the image forming device 111 or 211 and the opticaldevice 120, 320 or 520. In addition, a light flux which is convertedinto parallel light in the optical system 112 or 254 is incident to, isguided, and is emitted from the optical device 120, 320 or 520. Inaddition, the optical device 120, 320 or 520 is of a semi-transmissivetype (a see-through type). Specifically, at least optical device parts(more specifically, light guide plates 121 or 321 and second deflectionunits 140 or 340 described later) facing both eyes of the observer aresemi-transmissive (see-through).

In addition, in Embodiment 1 or Embodiments 2 to 7 described later,among light beams (central light beams CL) which are emitted from thecenter of the image forming device 111 or 211 and pass through a node onthe image forming device side of the optical system 112 or 254, a pointwhere a central incident light beam which is perpendicularly incident tothe optical device 120 or 320 is incident to the optical device 120, 320or 520 is set as an optical device central point O.

In addition, an axial line which passes through the optical devicecentral point O and is parallel to the axial line direction of theoptical device 120, 320 or 520 is set as an X axis, and an axial linewhich passes through the optical device central point O and conforms tothe normal line of the optical device 120, 320 or 520 is set as a Yaxis. In addition, a central point of the first deflection unit 130 or330 described below is the optical device central point O. That is tosay, as shown in FIG. 5, in the image display apparatus 100, 200, 300,400 or 500, the central incident light beam CL which is emitted from thecenter of the image forming device 111 or 211 and passes through thenode on the image forming device side of the optical system 112 or 254vertically runs into the light guide plate 121 or 321. In other words,the central incident light beam CL is incident to the light guide plate121 or 321 at an incidence angle of 0°. In addition, in this case, acenter of a displayed image conforms to the perpendicular line directionof the first surface 122 or 322 of the light guide plate 121 or 321.

In addition, in Embodiment 1 or Embodiments 2 to 12 described later, thedimming device 700 which adjusts a light amount of ambient lightincident from the outside is disposed on an opposite side to the sidewhere the image forming device 111 or 211 of the optical device 120, 320or 520 is disposed. Specifically, the dimming device 700 which is a kindof light shutter is fixed to the optical device 120, 320 or 520(specifically, a protection member (protection plate) 126 or 326 forprotecting the light guide plate 121 or 321 or a semi-transmissivemirror 520) using an adhesive 707. In addition, the dimming device 700is disposed in a region of the optical device 120, 320 or 520 on anopposite side to the observer. Further, the protection member (aprotection plate) 126 or 326 is adhered to the second surface 123 or 323of the light guide plate 121 or 321 by an adhesive member 127 or 327,and the first deflection unit 130 or 330 and the second deflection unit140 or 340 are covered by the protection member (a protection plate) 126or 326.

The optical device 120 or 320 in the Embodiment 1 or Embodiments 2 to 4and Embodiments 6 to 12 described later includes (a) the light guideplate 121 or 321 that causes incident light to propagate to an insidethereof through total reflection and to be emitted therefrom, (b) thefirst deflection unit 130 or 330 that deflects the light incident to thelight guide plate 121 or 321 such that the light incident to the lightguide plate 121 or 321 is totally reflected inside the light guide plate121 or 321, and (c) the second deflection unit 140 or 340 that causesthe light which has propagated inside the light guide plate 121 or 321through the total reflection to undergo a plurality of deflections suchthat the light which has propagated inside the light guide plate 121 or321 through the total reflection is emitted from the light guide plate121 or 321. In addition, the second deflection unit 140 or 340 islocated in a projection image of the dimming device 700.

Here, in Embodiment 1, the first deflection unit 130 and the seconddeflection unit 140 are disposed inside the light guide plate 121. Inaddition, the first deflection unit 130 reflects light incident to thelight guide plate 121, and the second deflection unit 140 causes thelight which has propagated inside the light guide plate 121 through thetotal reflection to undergo a plurality of transmissions andreflections. In other words, the first deflection unit 130 functions asa reflective mirror, and the second deflection unit 140 functions as asemi-transmissive mirror. More specifically, the first deflection unit130 disposed inside the light guide plate 121 is made of aluminum (Al),and includes a light reflection film (a kind of mirror) which reflectslight incident to the light guide plate 121. On the other hand, thesecond deflection unit 140 provided inside the light guide plate 121includes a multi-layer laminate structure in which a plurality ofdielectric laminate films are laminated. The dielectric laminate filmincludes, for example, a TiO₂ film which is a high dielectric constantmaterial, and a SiO₂ film which is a low dielectric constant material.The multi-layer laminate structure in which a plurality of dielectriclaminate films are laminated is disclosed in JP-T-2005-521099. Althoughsix-layer dielectric laminate films are shown in the figures, thepresent disclosure is not limited thereto. A thin piece made of the samematerial as a material of the light guide plate 121 is interposedbetween the dielectric laminate film and the dielectric laminate film.In addition, in the first deflection unit 130, parallel light incidentto the light guide plate 121 is reflected (or diffracted) such that theparallel light incident to the light guide plate 121 is totallyreflected inside the light guide plate 121. On the other hand, in thesecond deflection unit 140, the parallel light which has propagatedinside the light guide plate 121 through the total reflection undergoesa plurality of reflections (diffractions) and is emitted from the lightguide plate 121 toward the pupil 21 of the observer in a parallel lightstate.

In relation to the first deflection unit 130, a part 124 in which thefirst deflection unit 130 of the light guide plate 121 is provided maybe cut so as to provide a tilt surface on which the first deflectionunit 130 is formed in the light guide plate 121, and the cut part 124 ofthe light guide plate 121 may be adhered to the first deflection unit130 after a light reflection film is vacuum-deposited on the relatedtilt surface. In addition, in relation to the second deflection unit140, a multi-layer laminate structure in which the same material (forexample, glass) as a material of the light guide plate 121 and aplurality of dielectric laminate films (can be formed in a vacuumdeposition method, for example) are laminated may be manufactured, apart 125 on which the second deflection unit 140 is provided in thelight guide plate 121 may be cut so as to form a tilt surface, and themulti-layer laminate structure may be adhered to the related tiltsurface and be polished so as to trim the exterior. In this way, it ispossible to obtain the optical device 120 in which the first deflectionunit 130 and the second deflection unit 140 are provided inside thelight guide plate 121.

Here, in Embodiment 1 or Embodiments 2 to 4 and Embodiments 6 to 12described later, the light guide plate 121 or 321 made of optical glassor a plastic material has two parallel surfaces (the first surface 122or 322 and the second surface 123 or 323) which extend in parallel tothe light propagation direction (X axis) through the total internalreflection of the light guide plate 121 or 321. The first surface 122 or322 faces the second surface 123 or 323. In addition, parallel light isincident from the first surface 122 or 322 corresponding to a lightincidence surface, then propagates inside the light guide plate throughtotal reflection, and is emitted from the first surface 122 or 322corresponding to a light emission surface. However, the presentdisclosure is not limited thereto, and the light incidence surface maybe formed by the second surface 123 or 323, and the light emissionsurface may be formed by the first surface 122 or 322.

In Embodiment 1 or Embodiment 3 described later, the image formingdevice 111 is an image forming device with a first configuration, andhas a plurality of pixels arranged in a two-dimensional matrix state.Specifically, the image forming device 111 includes a reflective spatiallight modulation device 150, and a light source 153 constituted by alight emitting diode emitting white light. Each image forming device 111is entirely accommodated in a casing 113 (indicated by the dot chainline in FIG. 1), an opening (not shown) is provided in the relatedcasing 113, and light is emitted from the optical system (a parallellight emitting optical system or a collimating optical system) 112 viathe opening. The reflective spatial light modulation device 150 includesa liquid crystal display (LCD) 151 formed from an LCOS which is a lightvalue, and a polarization beam splitter 152 which reflects some of lightfrom the light source 153 so as to be guided to the liquid crystaldisplay 151 and transmits some of light reflected by the liquid crystaldisplay 151 therethrough so as to be guided to the optical system 112.The liquid crystal display 151 includes a plurality (for example,640×480) of pixels (liquid crystal cells) arranged in a two-dimensionalmatrix state. The polarization beam splitter 152 has an existingconfiguration and structure. Non-polarized light emitted from the lightsource 153 runs into the polarization beam splitter 152. A Ppolarization component passes through the polarization beam splitter 152and is emitted outward. On the other hand, an S polarization componentis reflected by the polarization beam splitter 152 so as to be incidentto the liquid crystal display 151, is reflected inside the liquidcrystal display 151, and is emitted from the liquid crystal display 151.Here, of the light beams emitted from the liquid crystal display 151,the light beams emitted from the pixels displaying “white” include manyP polarization components, and the light beams emitted from the pixelsdisplaying “black” include many S polarization components. Therefore,the P polarization components of the light beams emitted from the liquidcrystal display 151 and running into the polarization beam splitter 152pass through the polarization beam splitter 152 and are guided to theoptical system 112. On the other hand, the S polarization components arereflected in the polarization beam splitter 152 and are returned to thelight source 153. The optical system 112 includes, for example, a convexlens and generates parallel light, and thus the image forming device 111(more specifically, the liquid crystal display 151) is disposed at alocation (position) corresponding to the focal length in the opticalsystem 112.

The frame 10 includes a front portion 11 which is disposed on the frontside of the observer, two temple portions 13 which are installed at bothends of the front portion 11 via hinges 12 so as to rotatably move, anda modern portion (also called a tip cell, an earmuff, or an ear pad) 14which is installed in a front end part of each of the temple portions13. In addition, a nose pad (not shown) is installed. In other words, anassembly of the frame 10 and the nose pad basically has substantiallythe same structure as typical glasses. Further, the respective casings113 are installed in the temple portions 13 so as to be attachable anddetachable using installation members 19. The frame 10 is manufacturedusing metal or plastic. In addition, the respective casings 113 may beinstalled in the temple portions 13 so as not to be attachable anddetachable using the installation members 19. Further, in an observerwho possesses and wears the glasses, the respective casings 113 may beinstalled in the temple portions of the frame of the glasses of theobserver so as to be attachable and detachable using the installationmembers 19. The respective casings 113 may be installed outside thetemple portions 13 or may be installed inside the temple portions 13.

In addition, wires (a signal line, a power supply line, and the like) 15extending from one of the image forming devices 111A extend outward fromthe front end part of the modern portion 14 via the temple portion 13and the inside of the modern portion 14 and are connected to a controldevice (a control circuit, or a control unit) 18. Further, each of theimage forming devices 111A and 111B includes a headphone portion 16, anda wire 16′ for the headphone portion extending from each of the imageforming devices 111A and 111B extends from the front end part of themodern portion 14 to the headphone portion 16 via the temple portion 13and the inside of the modern portion 14. More specifically, the wire 16′for the headphone portion extends from the front end part of the modernportion 14 to the headphone portion 16 so as to go around the back sideof the auricle. With this configuration, it is possible to provide aclean display instrument without giving an impression in which theheadphone portion 16 or the wire 16′ for the headphone portion isdisposed in a disorderly manner.

The wires (a signal line, a power supply line, and the like) 15 areconnected to the control device (control circuit) 18 as described above.The control device 18 includes an image information storage device 18A.In addition, processes for displaying images are performed in thecontrol device 18. The control device 18 and the image informationstorage device 18A may be formed using existing circuits.

In addition, the imaging apparatus 17 including a solid-state imagingelement formed using a CCD or a CMOS sensor and a lens (not shown) isinstalled in a central part 11′ of the front portion 11 via anappropriate installation member (not shown). A signal from the imagingapparatus 17 is sent to, for example, the image forming device 111A viaa wire (not shown) extending from the imaging apparatus 17.

The dimming device 700 in Embodiment 1 includes a light shutter in whicha light transmission control material layer 705 is formed of a liquidcrystal material layer. In other words, the dimming device 700 includesa transparent first substrate 701 opposite to the optical device 120, atransparent second substrate 703 opposite to the first substrate 701,electrodes 702 and 704 respectively provided on the first substrate 701and the second substrate 703, and the light transmission controlmaterial layer 705 sealed between the first substrate 701 and the secondsubstrate 703. Here, the first substrate 701 and the second substrate703 are made of a plastic material. In addition, the first electrode 702and the second electrode 704 include transparent electrodes made ofindium tin oxide (ITO), and are formed using a combination of a PVDmethod such as a sputtering method and a lift-off method. Further, thelight transmission control material layer 705 is formed of,specifically, a liquid crystal material layer using a TN (TwistedNematic) type liquid crystal material. The first electrode 702 and thesecond electrode 704 are so-called beta electrodes which are notpatterned. The first electrode 702 and the second electrode 704 areconnected to the control device 18 via a connector and a wire (neithershown). Outer edge parts of the two substrates 701 and 703 are sealed bya sealing agent 706. Further, the first substrate 701 of the dimmingdevice 700 is adhered to a protection member 126 (protecting the lightguide plate 121) by an adhesive 707. In addition, polarization films arerespectively bonded to the outer surface of the first substrate 701 andthe outer surface of the second substrate 703, and these polarizationfilms are not shown. Further, the first substrate 701 of the dimmingdevice 700 is made to be shorter than the light guide plate 121, and thefirst substrate 701 of the dimming device 700 is fixed to the protectionmember 126 by the adhesive 707. The adhesive 707 is disposed at theouter edge part of the first substrate 701. This is also the same forthe embodiments described in the following. Furthermore, the opticaldevice 120 and the dimming device 700 are disposed in this order fromthe observer.

The light transmittance of the dimming device 700 can be controlled byvoltages applied to the first electrode 702 and the second electrode704. Specifically, for example, when a voltage is applied to the firstelectrode 702 in a state where the second electrode 704 is grounded, anarrangement state of liquid crystals in the liquid crystal materiallayer forming the light transmission control material layer 705 varies,and thereby the light transmittance of the liquid crystal material layervaries (refer to FIGS. 4A and 4B). Voltages applied to the firstelectrode 702 and the second electrode 704 can be controlled by theobserver operating a control knob provided in the control device 18. Inother words, the light transmittance of the dimming device 700 may beadjusted while the observer observes an image from the optical device120 or 320.

In addition, in the display instrument of Embodiments 1 to 12, or in theimage display method of Embodiments 1 to 12, a light amount of ambientlight incident from the outside is reduced by the dimming device 700 ina first mode in which an image captured by the imaging apparatus 17 isdisplayed on the image display apparatus 100, 200, 300, 400 or 500. Inaddition, in the first mode, the image display apparatus 100, 200, 300,400 or 500 functions as anon-transmissive type. FIG. 6 shows theexternal world viewed through the optical device (a light guide unit)120, 320 or 520. Here, a “subject A” imaged by the imaging apparatus 17is set to a screwdriver placed under the tools. In addition, the grippart and the front end part of the screwdriver are set as feature pointsof the screwdriver which is the subject A. In the first mode, theoverall image captured by the imaging apparatus 17 is displayed in theimage forming devices 111A and 111B. In the first mode, an image (animage viewed in the optical device 120, 320 or 520 by the observer)displayed on the image display apparatus 100, 200, 300, 400 or 500 isshown in FIG. 7A.

In addition, in the first mode, data regarding a subject (specifically,the subject A in this case) imaged by the imaging apparatus 17 may becompared with information stored in the image information storage device18A, and information (specifically, character information such as a“screwdriver”) corresponding to the data regarding the subject (thesubject A) conforming to the information stored in the image informationstorage device 18A may be displayed around the subject A as shown inFIG. 7A, or be displayed so as to overlap the subject A. Alternatively,only the image captured by the imaging apparatus 17 may be displayedwithout displaying this information.

Here, the data regarding the subject imaged by the imaging apparatus maybe, for example, data of extracted feature points of the subject imagedby the imaging apparatus 17. In addition, the information stored in theimage information storage device may be, for example, data of featurepoints of various objects. Further, specifically, for example, acomparison may be performed with regard to whether extracted featurepoints of the subject imaged by the imaging apparatus conform to featurepoints stored in the image information storage device.

Alternatively, in the first mode, data regarding a subject imaged by theimaging apparatus 17 may be compared with information stored in theimage information storage device 18A, and an image of the subject (thesubject A in this example) conforming to the information stored in theimage information storage device 18A may be displayed on the imagedisplay apparatus 100, 200, 300, 400 or 500 in a state where a lightamount of ambient light incident from the outside is reduced by thedimming device 700 (that is, in a state where the first mode iscontinued) (refer to FIG. 7B). In this case, an enhancement process (forexample, a color being added to the outline of the subject A) may beperformed on the image of the subject A. Alternatively, data regardingthe subject imaged by the imaging apparatus 17 may be compared with theinformation stored in the image information storage device 18A, andinformation (specifically, for example, character data such as a“screwdriver”) corresponding to the data regarding the subject may bedisplayed on the image display apparatus 100, 200, 300, 400 or 500 in astate where a light amount of ambient light incident from the outside isreduced by the dimming device 700, that is, an image of the externalenvironment is viewed in the optical device (a light guide unit) 120,320 or 520 (that is, in a state where the first mode is continued). Morespecifically, in the first mode, the information corresponding to thedata regarding the subject is displayed so as to overlap the image ofthe subject in the image displayed on the optical device 120, 320 or 520or around the image of the subject (refer to FIG. 8), and this will bedescribed later in detail.

In addition, in the first mode, when a light amount of ambient lightincident to the dimming device is “1”, a light amount of the ambientlight passing through the dimming device is 0.1 or less, and preferably0.05 or less.

Next, an operation mode of the image display apparatus 100, 200, 300,400 or 500 is switched from the first mode to a second mode. The modeswitching between the first mode and the second mode may be performed byinputting sound using a provided microphone (not shown) (an instructionbased on an observer's voice). Alternatively, the mode switching may beperformed using a provided infrared-ray emitting and receiving device(not shown), and, specifically, may be performed by detecting blinkingof the observer using the infrared-ray emitting and receiving device. Inthis second mode, the image display apparatus 100, 200, 300, 400 or 500functions as a semi-transmissive type, and, data regarding the subjectimaged by the imaging apparatus 17 may be compared with the informationstored in the image information storage device 18A, and information(specifically, for example, character data such as a “screwdriver”)corresponding to the data regarding the subject may be displayed on theimage display apparatus in a state where a light amount of ambient lightincident from the outside is not reduced by the dimming device 700, thatis, the external world are viewed through the optical device (a lightguide unit) 120, 320 or 520. More specifically, in the second mode, theinformation corresponding to the data regarding the subject is displayedso as to overlap the subject viewed from the dimming device 700 andoptical device 120, 320 or 520 or around the subject (refer to FIG. 8),and this will be described later in detail.

In the second mode, when a light amount of ambient light incident to thedimming device 700 is “1”, a light amount of the ambient light passingthrough the dimming device 700 is 0.3 to 0.8, and preferably 0.5 to 0.8.

Alternatively, the operation mode of the image display apparatus 100,200, 300, 400 or 500 is switched from the first to a third mode. Themode switching between the first mode and the third mode may beperformed in the same method as the mode switching between the firstmode and the second mode. Here, in the third mode, data regarding thesubject imaged by the imaging apparatus 17 may be compared with theinformation stored in the image information storage device 18A, and animage (specifically, an image of the subject A) of the subject havingdata corresponding to information stored in the image informationstorage device 18A may be displayed on the image display apparatus 100,200, 300, 400 or 500 in a state where a light amount of ambient lightincident from the outside is not reduced by the dimming device 700, thatis, the image display apparatus functions as a semi-transmissive typeand the external world are viewed through the optical device (lightguide unit) 120, 320 or 520. More specifically, in the third mode, theimage of the subject A is displayed so as to overlap the subject Aviewed through the dimming device 700 and the optical device 120, 320 or520 (refer to FIG. 9).

In the third mode, when a light amount of ambient light incident to thedimming device 700 is “1”, a light amount of the ambient light passingthrough the dimming device 700 is 0.1 to 0.6, and preferably 0.3 to 0.4.

Here, in the third mode, the subject viewed through the dimming device700 and the optical device 120, 320 or 520 overlaps the image of thesubject displayed on the image display apparatus 100, 200, 300, 400 or500 by adjusting the image of the subject displayed on the image displayapparatus 100, 200, 300, 400 or 500. Specifically, the image of thesubject displayed on the image display apparatus 100, 200, 300, 400 or500 may undergo enlargement and reduction processes, a rotation process,and a movement process while viewing the subject through the dimmingdevice 700 and the optical device 120, 320 or 520. More specifically, animage data process may be performed based on an affine transform matrix.More specifically, the image displayed on the optical device 120, 320 or520 is moved horizontally and vertically, is rotatably moved, or isenlarged and reduced using a switch (not shown) disposed in the controldevice 18. Thereby, a display position correcting signal is generated inthe control device 18, and an image signal is superimposed on thedisplay position correcting signal. In the first mode, the image displayapparatus 100, 200, 300, 400 or 500 displays the informationcorresponding to the data regarding the subject so as to overlap theimage of the subject in the image displayed on the optical device 120,320 or 520 or around the image of the subject, and, in the second mode,the image display apparatus 100, 200, 300, 400 or 500 displays theinformation corresponding to the data regarding the subject so as tooverlap the subject viewed through the dimming device 700 and theoptical device 120, 320 or 520 or around the subject; however, theabove-described processes may be performed before this display.

In addition, in a case where the subject viewed through the dimmingdevice 700 and the optical device 120, 320 or 520 overlaps the image ofthe subject displayed on the image display apparatus 100, 200, 300, 400or 500, as shown in FIG. 9, overlapping with the subject A may beperformed, or, as shown in FIG. 10, an image which is a portion of theimage captured by the imaging apparatus 17 and includes a specificsubject (the subject A) may be displayed on the image display apparatus100, 200, 300, 400 or 500. In addition, in FIG. 10, a portion of theimage captured by the imaging apparatus 17 is indicated by the whiterange.

Alternatively, in the third mode, the image of the subject displayed onthe image display apparatus 100, 200, 300, 400 or 500 is adjusted suchthat the image of the subject displayed on the image display apparatusis smaller than the subject viewed through the dimming device 700 andthe optical device 120, 320 or 520 (refer to FIG. 11). In addition, inFIG. 11, the reduced image is indicated by the white range.

In addition, in a binocular type in which two image display apparatusesare provided, one image display apparatus (for example, a right eyeimage display apparatus) may perform the above-described operations, andthe other image display apparatus (for example, a left eye image displayapparatus) may be in a state where a light amount of ambient lightincident from the outside is not reduced by the dimming device 700 atall times (refer to FIG. 6).

In the display instrument or the image display method of Embodiment 1,the dimming device which adjusts alight amount of ambient light incidentfrom the outside is disposed in the optical device, and, in the firstmode in which an image captured by the imaging apparatus is displayed onthe image display apparatus, a light amount of ambient light incidentfrom the outside is reduced by the dimming device. In other words, thedisplay instrument can be used as both the non-transmissive imagedisplay apparatus and the semi-transmissive image display apparatus onthe basis of control of operations and non-operations of the dimmingdevice. In addition, since a light amount of ambient light incident fromthe outside is reduced by the dimming device, it is possible to match anexternal object with a displayed image with high accuracy.

Embodiment 2

Embodiment 2 is a modification of Embodiment 1. As shown in FIG. 12which is a conceptual diagram of the image display apparatus 200 in thedisplay instrument (head mounted display) of Embodiment 2, the imageforming device 211 includes an image forming device with the secondconfiguration in Embodiment 2. In other words, alight source 251 and ascanning unit 253 which scans parallel light emitted from the lightsource 251 are provided. More specifically, the image forming device 211includes (i) the light source 251, (ii) a collimating optical system 252which converts light emitted from the light source 251 into parallellight, (iii) the scanning unit 253 which scans the parallel lightemitted from the collimating optical system 252, and (iv) a relayoptical system 254 which relays the parallel light scanned by thescanning unit 253 so as to be emitted. In addition, each image formingdevice 211 is entirely accommodated in a casing 213 (indicated by thedot chain line in FIG. 12), an opening (not shown) is provided in therelated casing 213, and light is emitted from the relay optical system254 via the opening. Further, the respective casings 213 are installedin the temple portions 13 so as to be attachable and detachable usinginstallation members 19.

The light source 251 includes a light emitting element which emits whitelight. In addition, light emitted from the light source 251 is incidentto the collimating optical system 252 which has positive optical poweras a whole and is emitted as parallel light. Further, the parallel lightis reflected by a total reflection mirror 256, and undergoes horizontalscanning and vertical scanning by the scanning unit 253 including MEMSwhich can scan incident parallel light in a two-dimensional manner byusing a micromirror which freely rotates in a two-dimensional direction,thereby generating a kind of two-dimensional image and virtual pixels(the number of pixels may be the same as in Embodiment 1). In addition,the light from the virtual pixels passes through the relay opticalsystem (a parallel light emitting optical system) 254 formed of anexisting relay optical system, and a light flux converted into parallellight is incident to the optical device 120.

The optical device 120 which causes the light flux converted intoparallel light in the relay optical system 254 to be incident thereto,be guided and be emitted therefrom has the same configuration andstructure as the optical device described in Embodiment 1, and thusdetailed description thereof will be omitted. In addition, the displayinstrument of Embodiment 2 has substantially the same configuration andstructure as the display instrument of Embodiment 1 except for the imageforming device 211 is different, and thus detailed description thereofwill be omitted.

Embodiment 3

Embodiment 3 is also a modification of Embodiment 1. FIG. 13 is aconceptual diagram of the image display apparatus 300 in the displayinstrument (head mounted display) of Embodiment 3. In addition, FIG. 14is a schematic cross-sectional view illustrating an enlarged portion ofa reflective volume hologram diffraction grating. In Embodiment 3, theimage forming device 111 includes an image forming device with the firstconfiguration in the same manner as in Embodiment 1. Further, basicconfiguration and structure of the optical device 320 are the same asthe optical device 120 of Embodiment 1 except that configuration andstructures of the first deflection unit and the second deflection unitare different.

In Embodiment 3, the first deflection unit and the second deflectionunit are disposed on a surface of the light guide plate 321(specifically, the second surface 323 of the light guide plate 321). Inaddition, the first deflection unit diffracts light incident to thelight guide plate 321, and the second deflection unit causes the lightwhich has propagated inside the light guide plate 321 through totalreflection to undergo a plurality of diffractions. Here, the firstdeflection unit and the second deflection unit includes a diffractiongrating element, specifically, a reflective diffraction grating element,more specifically, a reflective volume hologram diffraction grating. Inthe following description, for convenience, the first deflection unitincluding the reflective volume hologram diffraction grating is referredto as a “first diffraction grating member 330”, and, for convenience,the second deflection unit formed by the reflective volume hologramdiffraction grating is referred to as a “second diffraction gratingmember 340”.

In addition, in Embodiment 3, or Embodiment 4 described later, the firstdiffraction grating member 330 and the second diffraction grating member340 are formed by laminating a single diffraction grating layer. Inaddition, an interference pattern corresponding to one kind ofwavelength band (or a wavelength) is formed on each diffraction gratinglayer made of a photopolymer material and is manufactured in a method inthe related art. A pitch of the interference pattern formed on thediffraction grating layer (diffraction optical element) is constant, andthe interference pattern is linear and is parallel to the Z axis. Inaddition, the axial lines of the first diffraction grating member 330and the second diffraction grating member 340 are parallel to the Xaxis, and the normal lines thereof are parallel to the Y axis.

FIG. 14 is a partial cross-sectional view illustrating an enlargedreflective volume hologram diffraction grating. An interference patternwith a slant angle ϕ is formed in the reflective volume hologramdiffraction grating. Here, the slant angle ϕ indicates an angle formedbetween the surface of the reflective volume hologram diffractiongrating and the interference pattern. The interference pattern is formedfrom the inside of the reflective volume hologram diffraction grating tothe surface. The interference pattern satisfies the Bragg condition.Here, the Bragg condition indicates a condition satisfying the followingEquation (A). In Equation (A), m indicates a positive integer, λindicates a wavelength, d indicates a pitch of the grating surface (aninterval in the normal direction of a virtual plane including theinterference pattern), and Θ indicates the complementary angle of anincidence angle to the interference pattern. In addition, in a casewhere light enters the diffraction grating member at an incidence angleΨ, a relationship between Θ, the slant angle ϕ, and the incidence angleΨ is as in Equation (B).m·λ=2·d·sin(Θ)  (A)Θ=90°−(ϕ+Ψ)  (B)

As described above, the first diffraction grating member 330 is disposedon (adhered to) the second surface 323 of the light guide plate 321, anddiffracts and reflects parallel light incident to the light guide plate321 such that the parallel light incident to the light guide plate 321from the first surface 322 is totally reflected inside the light guideplate 321. Further, as described above, the second diffraction gratingmember 340 is disposed on (adhered to) the second surface 323 of thelight guide plate 321, and causes the parallel light which haspropagated inside the light guide plate 321 through the total reflectionto undergo a plurality of diffractions and reflections and to be emittedfrom the first surface 322 in a parallel light state from the lightguide plate 321.

In addition, the parallel light propagates inside the light guide plate321 through the total reflection and is then emitted. At this time,since the light guide plate 321 is thin and a path along with the lighttravelling inside the light guide plate 321 is long, the number of totalreflections until reaching the second diffraction grating member 340 isdifferent depending on each angle of view. More specifically, of theparallel light beams incident to the light guide plate 321, the numberof reflections of a parallel light beam incident with an angle in adirection close to the second diffraction grating member 340 is smallerthan the number of reflections of a parallel light beam incident to thelight guide plate 321 with an angle in a direction distant from thesecond diffraction grating member 340. This is because the parallellight which is diffracted and reflected in the first diffraction gratingmember 330 and is incident to the light guide plate 321 at an angle in adirection close to the second diffraction grating member 340 has asmaller angle formed with the normal line of the light guide plate 321when the light propagating inside the light guide plate 321 runs intothe inner surface of the light guide plate 321 than the parallel lightincident to the light guide plate 321 at an angle in a reverse directionthereto. In addition, a shape of the interference pattern formed insidethe second diffraction grating member 340 and a shape of theinterference pattern formed inside the first diffraction grating member330 are symmetric with respect to a virtual plane perpendicular to theaxial line of the light guide plate 321. The surfaces of the firstdiffraction grating member 330 and the second diffraction grating member340 which do not face the light guide plate 321 are covered by aprotection member (a protection plate) 326 such that the firstdiffraction grating member 330 and the second diffraction grating member340 are prevented from being damaged. Further, the light guide plate 321and the protection member 326 are adhered to each other by an adhesive327 at the outer circumferential part. In addition, the light guideplate 321 may be protected by bonding a transparent protection film tothe first surface 322.

The light guide plate 321 in Embodiment 4 described later basically alsohas the same configuration and structure as the above-describedconfiguration and structure of the light guide plate 321.

The display instrument of Embodiment 3 has substantially the sameconfiguration and structure as the display instrument of Embodiment 1except that the optical device 320 is different as described above, andthus detailed description thereof will be omitted.

Embodiment 4

Embodiment 4 is a modification of Embodiment 3. FIG. 15 is a conceptualdiagram of an image display apparatus in the display instrument (headmounted display) of Embodiment 4. The light source 251, the collimatingoptical system 252, the scanning unit 253, the parallel light emittingoptical system (the relay optical system 254), and the like in the imagedisplay apparatus 400 of Embodiment 4 have the same configurations andstructures (the image display apparatus with the second configuration)as in Embodiment 2. Further, the optical device 320 in Embodiment 4 hasthe same configuration and structure as the optical device 320 inEmbodiment 3. The display instrument of Embodiment 4 has substantiallythe same configuration and structure as the display instrument ofEmbodiment 2 except for the above-described differences, and thusdetailed description thereof will be omitted.

Embodiment 5

Embodiment 5 is a modification of the image display apparatus inEmbodiments 1 to 4. FIG. 16 is a schematic diagram of a displayinstrument of Embodiment 5 viewed from the front side, and FIG. 17 is aschematic diagram thereof viewed from the top side.

In Embodiment 5, the optical device 520 forming the image displayapparatus 500 includes a semi-transmissive mirror which allows lightemitted from the image forming devices 111A and 111B to be incidentthereto and to be emitted therefrom toward the pupil 21 of the observer.In addition, although, in Embodiment 5, a structure is employed in whichthe light emitted from the image forming devices 111A and 111Bpropagates inside a transparent member 521 such as a glass plate or aplastic plate and is incident to the optical device 520(semi-transmissive mirror), a structure may be employed in which thelight propagates through the air and is incident to the optical device520. Further, the image forming device may be the image forming device211 described in Embodiment 2.

The respective image forming devices 111A and 111B are installed in thefront portion 11 by using, for example, screws. In addition, the member521 is installed in each of the image forming devices 111A and 111B, theoptical device 520 (a semi-transmissive mirror) is installed in themember 521, and the dimming device 700 is installed in the opticaldevice 520 (a semi-transmissive mirror). The display instrument ofEmbodiment 5 has substantially the same configuration and structure asthe display instrument of Embodiments 1 to 4 except for theabove-described differences, and thus detailed description thereof willbe omitted.

Embodiment 6

Embodiment 6 is also a modification of Embodiments 1 to 4. FIG. 18A is aschematic diagram of the display instrument of Embodiment 6 viewed fromthe top side. In addition, FIG. 18B is a schematic diagram illustratingcircuits which control an illuminance sensor.

The display instrument of Embodiment 6 further includes a firstilluminance sensor (an environmental illuminance measuring sensor) 801which measures the illuminance of an environment in which the displayinstrument is placed, and the light transmittance of the dimming device700 is controlled based on a measurement result of the first illuminancesensor 801. In addition, the luminance of an image formed by the imageforming device 111 or 211 is controlled independently based on ameasurement result of the first illuminance sensor 801. The firstilluminance sensor 801 having an existing configuration and structuremay be disposed, for example, at an outer end part of the optical device120 or 320 or at the outer end part of the dimming device. The firstilluminance sensor 801 is connected to the control device 18 via aconnector and a wire (neither shown). The control device 18 includescircuits which control the first illuminance sensor 801. The circuitscontrolling the first illuminance sensor 801 include an illuminancecalculation circuit which receives a measurement value from the firstilluminance sensor 801 and obtains an illuminance, a comparisoncalculation circuit which compares a value of the illuminance obtainedby the illuminance calculation circuit with a standard value, and anenvironmental illuminance measuring sensor control circuit whichcontrols the dimming device 700 and/or the image forming device 111 or211 on the basis of a value obtained by the comparison calculationcircuit, and these circuits may be formed using existing circuits. Whenthe dimming device 700 is controlled, the light transmittance of thedimming device 700 is controlled, and, on the other hand, when the imageforming device 111 or 211 is controlled, the luminance of an imageformed by the image forming device 111 or 211 is controlled. Further,the control of the light transmittance in the dimming device 700 and thecontrol of the luminance in the image forming device 111 or 211 may beperformed independently or in correlation with each other.

For example, when a measurement result of the first illuminance sensor801 is equal to or more than a predetermined value (a first illuminancemeasurement value), the light transmittance of the dimming device 700 ismade to be equal to or less than a predetermined value (a first lighttransmittance). On the other hand, when a measurement result of thefirst illuminance sensor 801 is equal to or less than a predeterminedvalue (a second illuminance measurement value), the light transmittanceof the dimming device 700 is made to be equal to or more than apredetermined value (a second light transmittance). Here, the firstilluminance measurement value may be 10 lux, the first lighttransmittance may be any of 1% to 30%, the second illuminancemeasurement value may be 0.01 lux, and the second light transmittancemay be any one of 51% to 99%.

In addition, the first illuminance sensor (an environmental illuminancemeasuring sensor) 801 in Embodiment 6 may be applied to the displayinstrument described in Embodiments 2 to 5. Further, in a case where thedisplay instrument includes an imaging apparatus, the first illuminancesensor 801 may be formed using a light sensing element for exposuremeasurement provided in the imaging apparatus.

In the display instrument of Embodiment 6 or Embodiment 7 describedlater, the light transmittance of the dimming device is controlled basedon a measurement result of the first illuminance sensor (environmentalilluminance measuring sensor), the luminance of an image formed by theimage forming device is controlled based on a measurement result of thefirst illuminance sensor, the light transmittance of the dimming deviceis controlled based on a measurement result of a second illuminancesensor (transmission light illuminance measuring sensor), and theluminance of an image formed by the image forming device is controlledbased on a measurement result of the second illuminance sensor.Therefore, it is possible not only to give high contrast to an imageobserved by the observer but also to optimize an observation state of animage depending on the illuminance of the environment in which thedisplay instrument is placed.

Embodiment 7

Embodiment 7 is also a modification of Embodiments 1 to 4. FIG. 19A is aschematic diagram of the display instrument of Embodiment 7 viewed fromthe top side. In addition, FIG. 19B is a schematic diagram of circuitswhich control the illuminance sensor.

The display instrument of Embodiment 7 further includes the secondilluminance sensor (transmission light illuminance measuring sensor) 802which measures illuminance based on light transmitted through thedimming device from the external environment, that is, measures whetheror not environmental light is transmitted through the dimming device andis incident after being adjusted to a desired illuminance, and the lighttransmittance of the dimming device 700 is controlled based on ameasurement result of the second illuminance sensor 802. In addition,the luminance of an image formed by the image forming device 111 or 211is controlled independently based on a measurement result of the secondilluminance sensor 802. The second illuminance sensor 802 having anexisting configuration and structure is disposed further toward theobserver side than the optical device 120, 320 or 520. Specifically, thesecond illuminance sensor 802 may be disposed, for example, on a surfaceon the observer side of the light guide plate 121 or 321. The secondilluminance sensor 802 is connected to the control device 18 via aconnector and a wire (neither shown). The control device 18 includescircuits which control the second illuminance sensor 802. The circuitscontrolling the second illuminance sensor 802 include an illuminancecalculation circuit which receives a measurement value from the secondilluminance sensor 802 and obtains an illuminance, a comparisoncalculation circuit which compares a value of the illuminance obtainedby the illuminance calculation circuit with a standard value, and atransmission light illuminance measuring sensor control circuit whichcontrols the dimming device 700 and/or the image forming device 111 or211 on the basis of a value obtained by the comparison calculationcircuit, and these circuits may be formed using existing circuits. Whenthe dimming device 700 is controlled, the light transmittance of thedimming device 700 is controlled, and, on the other hand, when the imageforming device 111 or 211 is controlled, the luminance of an imageformed by the image forming device 111 or 211 is controlled. Further,the control of the light transmittance in the dimming device 700 and thecontrol of the luminance in the image forming device 111 or 211 may beperformed independently or in correlation with each other. Furthermore,in a case where a measurement result of the second illuminance sensor802 is not controlled to a desired illuminance in view of theilluminance of the first illuminance sensor 801, that is, themeasurement result of the second illuminance sensor 802 is not a desiredilluminance, or subtler illuminance adjustment is desired, the lighttransmittance of the dimming device may be adjusted while monitoring avalue of the second illuminance sensor 802.

In addition, the second illuminance sensor (a transmission lightilluminance measuring sensor) 802 in Embodiment 7 may be applied to thedisplay instrument described in Embodiments 2 to 4. Alternatively, thesecond illuminance sensor 802 in Embodiment 7 may be combined with thefirst illuminance sensors 801 in Embodiment 6, and, in this case,through various tests, the control of the light transmittance in thedimming device 700 and the control of the luminance of the image in theimage forming device 111 or 211 may be performed independently or incorrelation with each other.

Embodiment 8

Embodiment 8 is a modification of Embodiments 1 to 7, and relates to adisplay instrument according to the first example of the presentdisclosure. FIG. 20 is a conceptual diagram of the image displayapparatus of Embodiment 8; FIG. 21 is a schematic diagram of the displayinstrument (specifically, a head mounted display (HMD)) of Embodiment 8viewed from the top side; FIG. 22A is a schematic diagram of the displayinstrument of Embodiment 8 viewed from the lateral side; and FIG. 22B isa schematic diagram of optical device and dimming device parts viewedfrom the front side. In addition, in FIG. 22A, a light blocking memberis indicated by the dotted line. Further, FIG. 23 is a conceptualdiagram illustrating a modified example of the display instrument ofEmbodiment 8. Furthermore, the example shown in FIG. 21 is a modifiedexample of the display instrument of Embodiments 1 to 4, and the exampleshown in FIG. 23 is a modified example of the display instrument ofEmbodiment 5.

In the display instrument of the Embodiment 8, a light blocking member710 which blocks ambient light from being incident to the optical device120 is disposed in a region of the optical device 120 to which lightemitted from each of the image forming devices 111A and 111B isincident, specifically, a region in which the first deflection unit 130is provided. Here, the region of the optical device 120 to which lightemitted from each of the image forming devices 111A and 111B is incidentis included in a projection image of the light blocking member 710 ontothe optical device 120. In addition, a projection image of the endportion of the dimming device 700 onto the optical device 120 isincluded in the projection image of the light blocking member 710 ontothe optical device 120.

In Embodiment 8, the light blocking member 710 is disposed apart fromthe optical device 120 on an opposite side to the side of the opticaldevice 120 where each of the image forming devices 111A and 111B isdisposed. The light blocking member 710 is made of, for example, anopaque plastic material. The light blocking member 710 may integrallyextend from the casing 113 of each of the image forming devices 111A and111B, may be installed in the casing 113 of each of the image formingdevices 111A and 111B, may integrally extend from the frame 10, or maybe installed in the frame 10. In addition, in the shown example, thelight blocking member 710 integrally extends from the casing 113 of eachof the image forming devices 111A and 111B.

In the display instrument of the Embodiment 8, the light blocking memberwhich blocks ambient light from being incident to the optical device isdisposed in the region of the optical device to which light emitted fromthe image forming device is incident. Therefore, since the ambient lightis not originally incident to the region to which light emitted from theimage forming device is incident, specifically the ambient light is notincident to the first deflection unit 130, even if an incident lightamount of the ambient light varies due to an operation of the dimmingdevice, there is no deterioration in image display quality due tooccurrence of undesired stray light or the like in the displayinstrument.

Embodiment 9

Embodiment 9 is a modification of Embodiment 8. As shown in FIG. 24which is a conceptual diagram, in the display instrument of Embodiment9, a light blocking member 720 is disposed in the optical device 120part on an opposite side to the side where each of the image formingdevices 111A and 111B is disposed, unlike in Embodiment 8. Specifically,an opaque ink is printed in the optical device 120 (specifically, on theinner surface of the protection member 126) so as to form the lightblocking member 720. The display instrument of Embodiment 9 has the sameconfiguration and structure as the display instrument of Embodiment 8except for the above-described differences, and thus detaileddescription thereof will be omitted. In addition, the light blockingmember 720 of Embodiment 9 may be combined with the light blockingmember 710 of Embodiment 8. Further, the light blocking member 720 maybe formed on the outer surface of the protection member 126.

Embodiment 10

Embodiment 10 is also a modification of Embodiment 8. As shown in FIG.25 or 26 which is a conceptual diagram, in the display instrument ofEmbodiment 10, a light blocking member 730 is disposed in the dimmingdevice 700 unlike in Embodiments 8 and 9. Specifically, an opaque ink isprinted in the dimming device 700 so as to form the light blockingmember 730. In addition, in the example shown in FIG. 25, the lightblocking member 730 is formed on the outer surface of the firstsubstrate 701 of the dimming device 700, and, in the example shown inFIG. 26, the light blocking member 730 is formed on the inner surface ofthe first substrate 701 of the dimming device 700. The displayinstrument of Embodiment 10 has the same configuration and structure asthe display instrument of Embodiment 8 except for the above-describeddifferences, and thus detailed description thereof will be omitted. Inaddition, the light blocking member 730 of Embodiment 10 may be combinedwith the light blocking member 710 of Embodiment 8, the light blockingmember 730 of Embodiment 10 may be combined with the light blockingmember 720 of Embodiment 9, or, the light blocking member 730 ofEmbodiment 10, the light blocking member 710 of Embodiment 8, and thelight blocking member 720 of Embodiment 9 may be combined with eachother.

Embodiment 11

Embodiment 11 is a modification of Embodiments 8 to 10. In Embodiments 8to 10, the light transmission control material layer 705 is formed of aliquid crystal material layer. On the other hand, as shown in FIG. 27which is a conceptual diagram, in the display instrument of Embodiment11, a dimming device 700′ includes a light shutter in which a lighttransmission control material layer 705′ is formed of an inorganicelectroluminescence material layer. Here, a material of the inorganicelectroluminescence material layer uses tungsten oxide (WO₃). Inaddition, a first substrate 701′ and a second substrate 703′ forming thedimming device 700′ are formed of a transparent glass substrate such assoda-lime glass or super white glass, and the second substrate 703′ isthinner than the first substrate 701′. Specifically, the thickness ofthe second substrate 703′ is 0.2 mm, and the thickness of the firstsubstrate 701′ is 0.4 mm. The display instrument of Embodiment 11 hasthe same configuration and structure as the display instrument ofEmbodiments 8 to 10 except for the above-described differences, and thusdetailed description thereof will be omitted. In addition, the firstsubstrate 701′ of the dimming device 700′ and the protection member 126are adhered to each other by the adhesive 707 in the same manner as inEmbodiment 8.

Embodiment 12

Embodiment 12 relates to a display instrument according to the secondexample of the present disclosure, and relates to a modification ofEmbodiment 11. As shown in FIG. 28 which is a conceptual diagram, in thedisplay instrument of Embodiment 12, a dimming device 700″ includes afirst substrate 701″ opposite to the optical device 120, a secondsubstrate 703″ opposite to the first substrate 701″, electrodes 702″ and704″ respectively provided on the first substrate 701″ and the secondsubstrate 703″, and a light transmission control material layer 705″sealed between the first substrate 701″ and the second substrate 703″.In addition, the first substrate 701″ is also used as a constituentmember (specifically, the protection member 126) of the optical device120. In other words, the first substrate 701″ and the protection member126 are common members and are commonly used.

As above, in Embodiment 12, since the first substrate 701″ forming thedimming device 700″ is also used as a constituent member (the protectionmember 126) of the optical device 120, the weight of the entire displayinstrument can be reduced, and thus there is no concern that a user ofthe display instrument may feel discomfort.

The display instrument of Embodiment 12 has the same configuration andstructure as the display instrument of Embodiment 11, and thus detaileddescription thereof will be omitted. In addition, the light blockingmember in the display instrument of Embodiment 12 may be the sameconfiguration and structure as in the dimming device in the displayinstrument of Embodiments 8 to 10, and thus detailed description thereofwill be omitted.

As described above, although the present disclosure has been describedbased on the preferable embodiments, the present disclosure is notlimited to the embodiments. The configurations and structures of thedisplay instrument (a head mounted display) and the image displayapparatus described in the embodiments are only an example, and may beappropriately changed. For example, a surface relief hologram may bedisposed in the light guide plate (refer to U.S. Patent No. 20040062505A1). In the optical device 320, the diffraction grating element may usea transmissive diffraction grating element, and, one of the firstdeflection unit and the second deflection unit may be formed using areflective diffraction grating element, and the other thereof may beformed using a transmissive diffraction grating element. Alternatively,the diffraction grating element may use a reflective blazed-diffractiongrating element.

Although, in the embodiments, only the display instrument having theimage information storage device has been described, the presentdisclosure is not limited thereto, and a so-called cloud computer mayperform the function of the image information storage device. Inaddition, in this case, the display instrument is provided with acommunication unit, for example, a mobile phone or a smart phone, or thedisplay instrument is combined with the communication unit, and therebysending and receiving, and exchanging of a variety of information ordata can be performed between the cloud computer and the displayinstrument.

The dimming device may be disposed in the region of the optical devicefrom which light is emitted so as to be attachable and detachable. Inorder to dispose the dimming device so as to be attachable anddetachable, for example, the dimming device may be installed in theoptical device using screws made of transparent plastic, and may beconnected to the control circuit (for example, included in the controldevice 18 for controlling the image forming device) for controlling thelight transmittance of the dimming device via connectors and wires.

Depending on cases, a light shutter according to an electrodepositionmethod employing electrodeposition and dissociation phenomena caused bya reversible oxidation-reduction reaction of a metal (for example,silver particles) may be used. Specifically, Ag⁺ and I⁻ are dissolved inan organic solvent, an appropriate voltage is applied to electrodes soas to reduce Ag⁺, and thus Ag is deposited, thereby decreasing the lighttransmittance of the dimming device. On the other hand, Ag is oxidizedso as to be dissolved as Ag⁺, thereby increasing the light transmittanceof the dimming device. Alternatively, a light shutter employing a colorvariation of a material caused by the oxidation-reduction reaction of anelectrochromic material may be used. Specifically, the first electrodeand the second electrode are formed of so-called transparent betaelectrodes, and a first electrochromic material layer and a secondelectrochromic material layer are interposed between the first electrodeand the second electrode. The first electrochromic material layer isformed using, for example, a Prussian blue complex, and the secondelectrochromic material layer is formed using, for example, anickel-substituted Prussian blue complex. Alternatively, depending oncases, a light shutter which controls light transmittance using anelectrowetting phenomenon may be used. Specifically, the first electrodeis patterned in a comb shape, whereas the second electrode is formed ofa so-called transparent beta electrode, and an insulating first liquidand a conductive second liquid fill a gap between the first electrodeand the second electrode. In addition, a voltage is applied between thefirst electrode and the second electrode, and thereby a shape of aninterface between the first liquid and the second liquid varies, forexample, from a planar shape to a curved shape so as to control thelight transmittance.

In addition, the present disclosure may be implemented as the followingconfigurations.

-   (1) A head-mounted display device comprising:

an image display apparatus configured to display a captured image of aportion of an environment viewable through the head-mounted displaydevice; and

a dimmer configured to, while the captured image is displayed, allow aportion of ambient light from the environment to pass through thedimmer.

-   (2) The head-mounted display device of (1), further comprising:

at least one storage device configured to store display data; and

wherein the image display apparatus is further configured to display thedisplay data.

-   (3) The head-mounted display device of (2), wherein the display data    is selected from the group comprising a character, a word, a    sentence, a figure, an illustration, a still image and a moving    image.-   (4) The head-mounted display device of (1), further comprising:

a controller configured to, in response to receiving an indication toswitch from a first mode of operation to a subsequent mode of operation:

command the image display apparatus to switch from displaying thecaptured image to displaying the display data; and

command the dimmer to switch from allowing a first portion of ambientlight from the environment to pass through the dimmer to allowing asecond portion of ambient light from the environment to pass through thedimmer.

-   (5) The head-mounted display device of (4), wherein the display data    is at least one word describing at least one subject of the    environment viewable through the head-mounted display device.-   (6) The head-mounted display device of (4), wherein the display data    is at least one image corresponding at least one subject of the    environment viewable through the head-mounted display device.-   (7) The head-mounted display device of (4), wherein:

the first portion of ambient light to pass through the dimmer is lessthan the second portion of ambient light to pass through the dimmer.

-   (8) The head-mounted display device of (4), wherein the indication    to switch from the first mode of operation to the subsequent mode of    operation is received from a user of the head-mounted display    device.-   (9) The head-mounted display device of (8), further comprising:

a microphone configured to receive a voice command from the user toswitch from the first mode of operation to a subsequent mode ofoperation.

-   (10) The head-mounted display device of (8), further comprising:

an infrared receiver configured to receive a eye-blinking command fromthe user to switch from the first mode of operation to a subsequent modeof operation.

-   (11) A method of displaying information on a head-mounted display    device, the method comprising:

displaying a captured image of a portion of an environment viewablethrough the display device; and

dimming ambient light received through the head-mounted display devicefrom the environment while displaying the captured image.

-   (12) The method of (11), further comprising:

displaying display data stored in at least one storage device.

-   (13) The method of (12), wherein the display data is selected from    the group comprising a character, a word, a sentence, a figure, an    illustration, a still image and a moving image.-   (14) The method of (12), further comprising:

in response to receiving an indication to switch from a first mode ofoperation to a subsequent mode of operation:

switching from displaying the captured image to displaying the displaydata; and

switching from dimming the ambient light received through the displaydevice from the environment by a first amount to dimming the ambientlight received through the display device from the environment by asecond amount.

-   (15) The method of (14), wherein the display data is at least one    word describing at least one subject of the environment viewable    through the display device.-   (16) The method of (14), wherein the display data is at least one    image corresponding to at least one subject of the environment    viewable through the display device.-   (17) The method of (14), wherein the first amount more than the    second amount.-   (18) The method of (14), wherein the indication to switch from the    first mode of operation to a subsequent mode of operation is    received from a user of the head-mounted display device.-   (19) The method of (18), wherein the indication from the user is a    voice command or an eye-blinking command.-   (20) A head-mounted display device comprising:

display means for displaying a captured image of a portion of anenvironment viewable through the display device; and

dimming means for dimming ambient light received through thehead-mounted display device from the environment while displaying thecaptured image.

-   (21) Display Device

A display instrument including

(i) a frame that is worn on a head part of an observer;

(ii) an image display apparatus that is installed in the frame; and

(iii) an imaging apparatus,

wherein the image display apparatus includes

-   -   (A) an image forming device;    -   (B) an optical device that allows light emitted from the image        forming device to be incident thereto, to be guided, and to be        emitted therefrom; and    -   (C) a dimming device that adjusts a light amount of ambient        light incident from the outside, and wherein, in a first mode in        which an image captured by the imaging apparatus is displayed on        the image display apparatus, the light amount of ambient light        incident from the outside is reduced by the dimming device.

-   (22) The display instrument set forth in (21), wherein, in the first    mode, the overall image or a portion thereof captured by the imaging    apparatus is displayed in the image forming device.

-   (23) The display instrument set forth in (21), further including an    image information storage device, wherein, in the first mode, data    regarding a subject imaged by the imaging apparatus is compared with    information stored in the image information storage device, and an    image of the subject conforming to the information stored in the    image information storage device is displayed on the image display    apparatus in a state where a light amount of ambient light incident    from the outside is reduced by the dimming device.

-   (24) The display instrument set forth in (23), wherein the data    regarding the subject imaged by the imaging apparatus is compared    with the information stored in the image information storage device,    and information corresponding to the data regarding the subject is    displayed on the image display apparatus.

-   (25) The display instrument set forth in any one of (21) to (24),    wherein, in the first mode, when a light amount of ambient light    incident to the dimming device is “1”, a light amount of the ambient    light passing through the dimming device is 0.1 or less.

-   (26) The display instrument set forth in any one of (21) to (25),    further including an image information storage device, wherein, in a    second mode different from the first mode, data regarding a subject    imaged by the imaging apparatus is compared with information stored    in the image information storage device, and information    corresponding to the data regarding the subject is displayed on the    image display apparatus in a state where a light amount of ambient    light incident from the outside is not reduced by the dimming    device.

-   (27) The display instrument set forth in (26), wherein, in the    second mode, information corresponding to the data regarding the    subject is displayed on the image display apparatus so as to overlap    the subject viewed through the dimming device and the optical device    or around the subject.

-   (28) The display instrument set forth in (26) or (27), further    including a microphone, wherein switching between the first mode and    the second mode is controlled by inputting sound using the    microphone.

-   (29) The display instrument set forth in (26) or (27), further    including an infrared-ray emitting and receiving device, wherein    switching between the first mode and the second mode is controlled    using the infrared-ray emitting and receiving device.

-   (30) The display instrument set forth in any one of (26) to (29),    wherein, in the second mode, when a light amount of ambient light    incident to the dimming device is “1”, a light amount of the ambient    light passing through the dimming device is 0.3 to 0.8.

-   (31) The display instrument set forth in any one of (21) to (29),    further including an image information storage device, wherein, in a    third mode different from the first mode, data regarding a subject    imaged by the imaging apparatus is compared with information stored    in the image information storage device, and an image of the subject    having data corresponding to information stored in the image    information storage device is displayed on the image display    apparatus in a state where a light amount of ambient light incident    from the outside is not reduced by the dimming device.

-   (32) The display instrument set forth in (31), wherein, in the third    mode, when a light amount of ambient light incident to the dimming    device is “1”, a light amount of the ambient light passing through    the dimming device is 0.1 to 0.6.

-   (33) The display instrument set forth in (31) or (32), wherein, in    the third mode, the image of the subject displayed on the image    display apparatus is adjusted so as to overlap the subject viewed    through the dimming device and the optical device with the image of    the subject displayed on the image display apparatus.

-   (34) The display instrument set forth in (31) or (32), wherein, in    the third mode, the image of the subject displayed on the image    display apparatus is adjusted such that the image of the subject    displayed on the image display apparatus is smaller than the subject    viewed through the dimming device and the optical device.

-   (35) The display instrument set forth in any one of (21) to (34),    further including a pair of image display apparatuses installed in    the frame, wherein one of the image display apparatuses is in a    state where a light amount of ambient light incident from the    outside is not reduced by the dimming device at all times.

-   (36) Image Display Method

An image display method using a display instrument including

(i) a frame that is worn on a head part of an observer;

(ii) an image display apparatus that is installed in the frame; and

(iii) an imaging apparatus, wherein the image display apparatus includes

-   -   (A) an image forming device;    -   (B) an optical device that allows light emitted from the image        forming device to be incident thereto, to be guided, and to be        emitted therefrom; and    -   (C) a dimming device that adjusts a light amount of ambient        light incident from the outside, the method including causing        the dimming device to reduce the light amount of ambient light        incident from the outside in a first mode in which an image        captured by the imaging apparatus is displayed on the image        display apparatus.

-   (37) The image display method set forth in (36), wherein the display    instrument further includes an image information storage device, and    wherein, in a second mode after performing the first mode, data    regarding a subject imaged by the imaging apparatus is compared with    information stored in the image information storage device, and    information corresponding to the data regarding the subject is    displayed on the image display apparatus in a state where a light    amount of ambient light incident from the outside is not reduced by    the dimming device.

-   (38) The image display method set forth in (36) or (37), wherein the    display instrument further includes an image information storage    device, and wherein, in a third mode after performing the first    mode, data regarding a subject imaged by the imaging apparatus is    compared with information stored in the image information storage    device, and an image of the subject having data corresponding to    information stored in the image information storage device is    displayed on the image display apparatus in a state where a light    amount of ambient light incident from the outside is not reduced by    the dimming device.

-   (39) The image display method set forth in (38), wherein, in the    third mode, the image of the subject displayed on the image display    apparatus is adjusted so as to overlap the subject viewed through    the dimming device and the optical device with the image of the    subject displayed on the image display apparatus.

-   (40) The image display method set forth in (38), wherein, in the    third mode, the image of the subject displayed on the image display    apparatus is adjusted such that the image of the subject displayed    on the image display apparatus is smaller than the subject viewed    through the dimming device and the optical device.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A display device adapted to be mounted on a partof a user's head, the display device comprising: an image displaysection configured to display a captured image of a portion of anenvironment viewable by the user through the display device when thedisplay device is mounted on the part of the user's head, the imagedisplay section comprising a first surface which faces an eye of theuser when the display device is worn on the part of the user's head anda second surface opposing the first surface and facing a protectionmember; a dimmer comprising a first electrode residing on the protectionmember, a second substrate, a second electrode residing on the secondsubstrate, and a light transmission control material layer, at least aportion of the light transmission control material layer residingbetween the first electrode and the second electrode, the dimmer beingconfigured to, while the captured image is displayed, allow an amount ofambient light from the environment to pass through the dimmer; and acontroller configured to process at least one feature of the capturedimage, and as a result of the processing: cause the image displaysection to present display data, and cause the dimmer to modify anamount of ambient light from the environment that is allowed to passthrough; wherein the dimmer is detachable from the display device. 2.The display device of claim 1, wherein the display data is selected fromthe group comprising a character, a word, a sentence, a figure, anillustration, a still image and a moving image.
 3. The display device ofclaim 1, wherein the controller is configured to, as a result of theprocessing, control the image display unit to switch from displaying thecaptured image to displaying the display data, and to control the dimmerto switch from allowing a first amount of ambient light from theenvironment to pass through the dimmer to allowing a second amount ofambient light from the environment to pass through the dimmer.
 4. Thedisplay device of claim 3, wherein the display data is at least one wordrelating to at least one subject of the environment viewable through thedisplay device.
 5. The display device of claim 3, wherein the displaydata is at least one image relating to at least one subject of theenvironment viewable through the display device.
 6. The display deviceof claim 3, wherein the first amount of ambient light allowed to passthrough the dimmer is less than the second amount of ambient lightallowed to pass through the dimmer.
 7. The display device of claim 3,wherein the controller is further configured to receive an indication toswitch from a first operation mode to a second operation mode from auser of the display device.
 8. The display device of claim 7, furthercomprising: a microphone configured to receive a voice command from theuser to switch from the first operation mode to the second operationmode.
 9. The display device of claim 7, further comprising: an infraredreceiver configured to receive an eye-blinking command from the user toswitch from the first operation mode to the second operation mode. 10.The display device of claim 1, wherein the controller is configured toswitch the display device from one of a plurality of operation modes toanother of the plurality of operation modes, and in at least one of theplurality of operation modes, the image display section isnon-transmissive.
 11. The display device of claim 1, wherein thecontroller is configured to switch the display device from one of aplurality of operation modes to another of the plurality of operationmodes, and in at least one of the plurality of operation modes, theimage display section is semi-transmissive.
 12. The display device ofclaim 11, wherein the plurality of operation modes comprises at leasttwo operation modes in which the image display section issemi-transmissive, and a first of the at least two operation modes isdifferent than a second of the at least two operation modes.
 13. Thedisplay device of claim 1, comprising at least one storage deviceconfigured to store information, and wherein the controller isconfigured to process the at least one feature of the captured image bycomparing the at least one feature of the captured image to informationstored by the at least one storage device, and to cause the imagedisplay section to present display data retrieved from the at least onestorage device as a result of the comparing.
 14. The display device ofclaim 1, wherein the second substrate is thinner than the protectionmember.
 15. The display device of claim 1, wherein the lighttransmission control material layer is formed of a liquid crystalmaterial layer.
 16. The display device of claim 1, wherein the lighttransmission control material layer is formed of an inorganicelectroluminescence material layer.
 17. The display device of claim 1,wherein at least one of the first substrate and the second substratecomprises transparent glass.